Regeneration of ion exchange resin and recovery of regenerant solution

ABSTRACT

An apparatus and method for regenerating spent ion exchange resin and recovering regenerant fluid is described. A regeneration system has a regeneration vat, a regeneration solution tank, a regenerant recovery tank, a chemical dispenser, a solids separator, a pH adjuster and a pump. The regeneration vat holds the spent resin and is connected to the regeneration solution tank to allow transfer of regenerant solution into the regeneration vat. Spent regenerant fluid travels to the regenerant recovery tank, where it is treated with chemicals provided from the chemical dispenser. The solids separator receives the treated regenerant liquid and separates precipitate flocs from the treated regenerant liquid. The concentration of chloride ions in the separated regenerant solution can be adjusted by the pH adjuster to form fresh regenerant solution. The pump pumps the fresh regenerant solution to the regenerant solution tank to regenerate additional spent cation exchange resin.

CROSS-REFERENCE

The present application is a divisional and claims priority to U.S.patent application Ser. No. 12/889,350, filed Sep. 23, 2010. U.S. patentapplication Ser. No. 12/889,350 is a continuation-in-part of U.S. Pat.No. 8,017,001, filed Jul. 16, 2007, which claims priority from U.S.Provisional Application No. 60/807,369, filed Jul. 14, 2006. U.S. patentapplication Ser. No. 12/889,350 also claims priority to U.S. ProvisionalApplication No. 61/305,945, filed Feb. 18, 2010. All four patentapplications are being incorporated by reference herein and in theirentireties.

BACKGROUND

Embodiments of the present invention relate to the regeneration of ionexchange resin with a regenerant solution and recovery of the spentregenerant solution.

Ion exchange resins are used to treat fluids that include gases andliquids to remove ions, contaminants, and dissolved solids. The resinscan be used in many different types of separation, purification, anddecontamination processes including water treatment, treatment of toxicliquids or gases, or other applications. The ion exchange resins can bein the form of organic polymer beads, membranes, or other structures,and can include (i) cation exchange resins which have functional groupsthat are strong or weak acid groups, and (ii) anion exchange resinswhich have functional groups which are strong or weak base groups. In atypical ion exchange resin system, the fluid to be treated is passedacross or through the ion exchange resin. For example, well or tap watercan be treated with an ion exchange resin to remove divalent orcontaminant ions to provide softened or purified water. The ion exchangeresin removes certain ions from the water and exchanges them for otherions in a reversible chemical reaction. For example, multivalent anddivalent ions such as, for example, Ca⁺², Mg⁺², and SO₄ ⁻² ions, can beremoved from the fluid being treated and exchanged for Na⁺ ions in theresin.

Besides water treatment, ion exchange resins can have many otherapplications. For example, in one application, ion exchange resins areused to remove poisonous metal (e.g., copper) and heavy metal (e.g.,lead or cadmium) ions from a solution, and replace them with moreinnocuous ions, such as sodium and potassium. Ion exchange resins canalso be used to remove organic contaminants from water; for example,using an activated charcoal filter to remove the chlorine mixed withanionic resin to remove organic contaminates. Still other ion exchangeresins remove organic ions, such as MIEX (magnetic ion exchange) resins.Still other applications of ion exchange resin systems include thetreatment of: salt water pre-treatment in desalination processes;industrial waste liquids and gases to remove hazardous ions andcompounds; waste from nuclear power plants to remove radioactive orother toxic materials; fluids to recover valuable metals; industrialdrying of gases; food industry applications such as wine-making andsugar manufacture; medical applications that include the development andpreparation of drugs and antibiotics, such as streptomycin and quinine;treatments for ulcers, TB, kidneys, and other organs; and the preventionof coagulation of blood and dextrose. Ion exchange processes can be usedto separate and purify metals, including separating uranium fromplutonium and other actinides, such as thorium, lanthanum, neodymium,ytterbium, samarium, and lutetium, from each other and the otherlanthanides. Ion exchange resins can also be used to catalyze organicreactions, such as in self-condensation reactions. Ion exchange resinsare also used in the manufacture of fruit juices (e.g., orange juice)where they are used to remove bitter-tasting components and so improvethe flavor. In the processing of sugar, ion exchange resins are used toconvert one type of sugar into another type of sugar and to decolorizeand purify sugar syrups. Ion exchange resins are also used in themanufacturing of pharmaceuticals, not only for catalyzing certainreactions but also for isolating and purifying pharmaceutical activeingredients.

In any of these applications, after a number of treatment cycles, theused ion exchange resin becomes spent or exhausted and needs to beregenerated to remove the ions which have exchanged into, andaccumulated in, the spent resin. Ion exchange resins contain a finitenumber of ion exchange sites, and the exchange capacity of the resinseventually becomes spent as the resins become saturated with ionsextracted from a fluid. An ion exchange resin can also lose itsefficiency from plugging up with solids, such as sand or otherparticles, which are present in the liquid being treated.

To regenerate the spent ion exchange resin, the spent resin is treatedwith a resin regenerant solution containing ions that exchange with theaccumulated ions in the resin to recharge the resin. The composition ofthe regenerant solution depends on the chemical composition of the ionexchange resin and type of ions accumulated in the resin. For example,spent cation exchange resin can be treated by soaking the resin in aregenerant solution comprising sodium chloride or potassium dissolved inwater to remove accumulated divalent ions and solids. The sodium orpotassium ions replace divalent ions such as calcium and magnesium whichare trapped in the ion exchange resin with sodium ions. Ion exchangeresins can also be regenerated with solutions comprising other forms ofchloride ions, such as hydrochloric acid. Oftentimes, afterregeneration, the ion exchange resin can be rinsed with fresh water orother liquids to displace residual regenerant solution. The regenerantsolution and rinse liquid both contain dissolved divalent ions whichcontaminate the regenerant solution and prevent its reuse. Similarly,spent anion exchange resins can also be treated with other types ofregenerant solutions and/or rinse liquids which also accumulate in thespent resins.

The disposal of spent regenerant solutions and rinse liquids intomunicipal wastewater systems creates environmental problems andincreases regeneration process costs. Municipal wastewater plants oftencannot remove all of the mineral hardness compounds, such as sodiumchloride, from the incoming water stream, and thus, these compounds arepassed out with the processed water into the environment to contaminaterivers, lakes and seas, or even ground water and surrounding land, withundesirable metallic ions. Also, the higher concentrations of totaldissolved salts in processed water, such as chloride, sodium and boronions in particular, limit reuse of such water in farming andagricultural applications. The contribution to municipal sewage of saltwater discharge from household ion exchange systems has reached suchmajor proportions that regulations are being promulgated on thereduction of salt use in the regeneration of ion exchange resins andprohibiting the discharge of brines to municipal sewage systems. Forexample, the discharge of salt solutions from ion exchange processesused in food, tanning and textile industries, and hospitals throughmunicipal wastewater systems can exceed thousands of tons of salt peryear. Also, disposal of spent regenerant solutions into the wastewatersystems creates a need for additional chemicals and fresh water to formnew regenerant solution, further increasing the costs associated withregenerating exchange resins.

For reasons including these and other deficiencies, and despite thedevelopment of various ion exchange regeneration systems, apparatus, andmethods, further improvements in the treatment of spent regenerantsolution and other waste liquids generated in the process ofregenerating ion exchange resins are continuously being sought.

SUMMARY

A regenerant recovery method is capable of recovering a spent regenerantsolution, by treating the spent regenerant solution with a regeneranttreatment composition to form treated regenerant liquid comprisingprecipitated flocs; separating the treated regenerant liquid to separatethe precipitated flocs from the supernatant; and transferring thesupernatant to a regenerant recovery tank.

In one exemplary method, fresh regenerant solution is passed acrossspent ion exchange resin, which can be any type of resin includingcation exchange resin or anion exchange resin, for sufficient time toregenerate the spent ion exchange resin and form fresh ion exchangeresin and spent regenerant solution. A regenerant treatment compositionis added to the spent regenerant solution to form a treated regenerantliquid. Precipitated compounds are separated from the treated regenerantliquid to form a separated or filtered regenerant solution. Theprecipitated compounds can be separated out using, for example, a filterpress or centrifuge. The pH of the treated or separated regenerantliquid can also be adjusted to allow recovery and recycling of theregenerant solution.

Instead of only treating spent regenerant solution, a regenerant wasteliquid can be formed by collecting spent regenerant solution, spentbackwash water which is used to backwash spent resin prior toregeneration, and/or spent rinse water which is used to rinse spentresin after regeneration. The regenerant waste liquid can be treated byadding the regenerant treatment composition to the regenerant wasteliquid to form treated regenerant liquid and the precipitated compoundscan be separated from the supernatant.

In still another version, a method of regenerating spent cation exchangeresin comprises preparing a fresh regenerant solution comprising sodiumions and chloride ions, and passing the regenerant solution across spentcation exchange resin to regenerate the spent cation exchange resin,thereby forming fresh cation exchange resin and spent regenerantsolution. For example, the fresh regenerant solution can be a solutionof sodium chloride. A regenerant treatment composition is dispensed intothe spent regenerant solution, the regenerant treatment compositioncomprising at least one hydroxide component and at least one carbonatecomponent, thereby forming treated regenerant liquid and precipitateflocs or flakes. The precipitate flocs are separated from the treatedregenerant liquid to form a separated regenerant solution. Theconcentration of the chloride ions in the separated regenerant solutionis adjusted to form fresh regenerant solution which can be used toregenerate additional spent cation exchange resin.

As one example, a suitable regenerant treatment composition can includecalcium hydroxide, sodium hydroxide, and sodium carbonate. The calciumand sodium hydroxide can be added in an amount sufficient to precipitateat least about 90% of the magnesium ions in the spent regenerantsolution to form a first precipitate compound comprising magnesiumhydroxide; and the sodium carbonate can be added in an amount sufficientto precipitate at least about 90% of the calcium ions in the spentregenerant solution to form a second precipitate compound comprisingcalcium carbonate.

Yet another process for regenerating spent ion exchange resin comprisesproviding a source of spent ion exchange resin in the form of aliquid-resin mixture; pumping the liquid-resin mixture to a regenerationvat with a non-abrasive resin transfer pump having pumping componentsthat do not abrade the spent ion exchange resin in the liquid-resinmixture; and pumping a regenerant solution through the spent resin inthe regeneration vat to regenerate the spent ion exchange resin to formfresh ion exchange resin. In one version, the non-abrasive resintransfer pump comprises a peristaltic pump.

In another version, a resin pumping process for transferring resin whileminimizing damage to the resin, comprises providing a flexible tubehaving a suction port and output port; connecting the suction port ofthe flexible tube to the liquid-resin mixture; connecting the outputport of the flexible tube to the regeneration vat; and squeezing theflexible tube in a direction from the suction port to the output port topump the liquid-resin mixture in the flexible tube to the regenerationvat.

In yet another version, the resin pumping process comprises providing aflow of pressurized water; constricting a flow of pressurized liquid toform a liquid jet stream; drawing resin through a suction port adjacentto the jet stream of water; and expanding the jet stream of water tohave a second velocity and second pressure, the second velocity beinglower than the first velocity and the second pressure being lower thanthe first pressure to pump the spent resin to the regeneration vat.Still a further version comprises passing the flow of pressurized fluidthrough the throat of a converging-diverging nozzle and passing thefluid jet stream through a divergent nozzle outlet.

In the resin pumping processes, a liquid-resin mixture can also bepumped be made by adding a liquid to the spent or regenerated resin in aliquid to resin volume ratio of from about 0.2:1 to about 4:1. Stillfurther, the liquid-resin mixture can be pumped out from a spent resinsump to a resin regeneration vat, from a resin regeneration vat to aregenerated resin storage tank or sump, or even to fill portable ionexchange tanks.

A resin regeneration system comprises a regeneration vat for holdingspent cation exchange resin and a regenerant solution tank for holdingfresh regenerant solution. The regenerant solution tank is connected tothe regeneration vat to allow transfer of the regenerant solution intothe regeneration vat to regenerate the spent cation exchange resin toform fresh cation exchange resin and spent regenerant solution. Aregenerant recovery tank comprises (i) a fluid inlet to receive thespent regenerant solution, and (ii) a fluid outlet to release treatedregenerant liquid. A chemical dispenser is provided to dispense aregenerant treatment composition into the spent regenerant solution inthe regenerant recovery tank to form treated regenerant liquid andprecipitate flocs. A solids separator is provided to receive the treatedregenerant liquid and separate the precipitate flocs from the treatedregenerant liquid to form a separated regenerant solution. A pH adjusteris provided to adjust the concentration of chloride ions in theseparated regenerant solution to form fresh regenerant solution. A pumpis provided to pump the fresh regenerant solution to the regenerantsolution tank to regenerate additional spent cation exchange resin.

In one version, the chemical dispenser comprises (i) a hopper comprisingan inlet to receive a regenerant treatment composition, and an outlet todispense the regenerant treatment composition; and (ii) a liquid channelto pass a flowing stream of spent regenerant solution past the outlet ofthe hopper to receive, and disperse therein, the dispensed regeneranttreatment composition passed to the flowing stream.

In one version, the regenerant recovery tank comprises (i) a fluid inletto receive the flowing stream of spent regenerant solution; (ii) acirculation mixer to mix the spent regenerant solution and dispersedregenerant treatment composition to form treated regenerant liquid andprecipitated compounds; and (iii) an outlet to release treatedregenerant liquid.

A solids separator to separate the precipitate flocs or precipitatedcompounds from the treated regenerant liquid to form separatedregenerant liquid. In one version, the solids separator comprises (i) aninlet to receive treated regenerant liquid; (ii) a pump to pump thetreated regenerant liquid to the inlet; (iii) a filter connected to theinlet to receive the treated regenerant liquid, the filter capable ofseparating precipitate flocs from a supernatant; and (iv) an outlet tooutput the supernatant comprising filtered regenerant solution.

The solids separator can be a centrifuge or filter press. For example,one version of a centrifuge comprises a bucket to hold a treatedregenerant liquid, the bucket having a cylindrical wall with an innercircumference. A rotatable shaft is mounted in the bucket, the rotatableshaft comprising a hollow tube having (i) an inlet to receive thetreated regenerant liquid, (ii) a plurality of openings extending alonga length of the hollow tube, and (iii) an outlet to output thecentrifuged solution. A plurality of blades extend radially outward fromthe rotatable shaft. A first magnetic levitation system is provided tomagnetically levitate the rotatable shaft and a second magneticlevitation system is provided to magnetically levitate the bucket. Amotor is provided to rotate the rotatable shaft causing the blades torotate and generate a centrifugal force in the solution in the bucket.

In one version, the first magnetic levitation system of the centrifugecomprises first and second magnets, the first magnet having a firstmagnetic pole that faces away from the shaft to hover above a secondmagnetic pole of the second magnet. In another version, the secondmagnetic levitation system comprises (i) a cylinder having first andsecond ends, the first end attached to the cylindrical wall of thebucket; (ii) an annular magnet attached to the second end of thecylinder, the annular magnet having a lower face and an upper face; and(iii) a basal magnet having an upward face that faces the lower face ofthe annular magnet, wherein the upward face has a polarity opposite tothe polarity of the lower face.

In still another aspect, a distillation apparatus comprises a heatsource to heat spent rinse water for distillation to form distilledwater. In one version, the distillation apparatus can include a thermaldistiller comprising a condenser housing and heat exchanger. Thecondenser housing comprises a condenser hood, gutter well, condensedwater tray, and cooling water tray. The condenser hood can have a slopedwall connected to a sidewall. In one version, the thermal distiller isconnected to an exhaust gas output from an engine to capture the heatfrom the exhaust gases of the engine. A gas transfer pipe is connectedto an exhaust pipe of the engine to direct exhaust gas to an inletmanifold of the heat exchanger. The inlet manifold feeds a plurality ofheat exchanger pipes in a heat exchanger tray, and the pipes terminatein an outlet manifold. In operation, spent rinse water is delivered tothe heat exchanger tray and the gutter well. The gas transfer pipe feedsexhaust gas into pipes of the heat exchanger causing the spent rinsewater in the heat exchanger tray to evaporate, rise-up, and thencondense on the internal condensing surfaces of the sloped wall andsidewall of condenser hood. The gutter well cascades water over theexternal surfaces of the condenser hood to cool off the condensingsurface. The evaporated water that condenses on the condenser hoodcomprises cleaned distilled water and is collected in the condensedwater tray. Spent rinse water used to cool the condensing surfaces iscollected in the cooling water tray.

DRAWINGS

These features, aspects, and advantages of the present invention willbecome better understood with regard to the following description,appended claims, and accompanying drawings, which illustrate examples ofthe invention. However, it is to be understood that each of the featurescan be used in the invention in general, not merely in the context ofthe particular drawings, and the invention includes any combination ofthese features, where:

FIG. 1 is a flowchart of an exemplary embodiment of (i) an ion exchangeprocess to remove ions and solids from a fluid using an ion exchangeresin, (ii) regeneration of the spent resin with a regenerant solution,and (iii) recovery and recycling of the spent regenerant solution;

FIG. 2 is a schematic diagram of an exemplary embodiment of an ionexchange apparatus comprising a column containing ion exchange resinthrough which a liquid is passed to treat the liquid;

FIG. 3A is a schematic diagram of a portion of an exemplary embodimentof a resin regeneration and recovery system for regenerating spent resinwith a regenerant solution;

FIG. 3B is a schematic diagram of another portion of the resinregeneration and recovery system of FIG. 3A;

FIG. 3C is a schematic diagram of a chemical dispenser that includes ahopper and an eductor for mixing solids of a regenerant treatmentcomposition into a flowing stream of spent regenerant solution;

FIG. 3D is a schematic diagram of a system controller for controllingthe resin regeneration and regenerant recovery system of FIGS. 3A to 3C;

FIGS. 4A to 4D are flowcharts of another exemplary embodiment of a resinregeneration and recovery process;

FIG. 5A is a schematic diagram of a portion of another exemplaryembodiment of a resin regeneration system for regenerating spent resin,and treating and recovering spent regenerant solution;

FIG. 5B is schematic diagram of another portion of the regeneration andrecovery system of FIG. 5A;

FIG. 5C is a schematic diagram of yet another portion of theregeneration and recovery system of FIGS. 5A and 5B;

FIGS. 6A to 6C are schematic cross-sectional diagrams of the side (6Aand 6B) and front (6C) of an exemplary embodiment of a non-abrasiveresin transfer pump that is a peristaltic pump, showing rotation of thespin rollers;

FIG. 7 is a schematic diagram of a resin transfer pump comprising adifferential pressure, venturi-type, injector pump;

FIG. 8A is an exploded schematic perspective view of a section of asolids separator comprising a filter press showing a plurality of filterplates that slide along a pair of rails;

FIG. 8B is a cross-sectional top view of the filter press of FIG. 8Ashowing the flow of treated regenerant liquid comprising precipitateflocs across the plates;

FIG. 9 is a schematic perspective view of a solids separator comprisinga centrifuge;

FIG. 10A is a perspective view of a thermal distiller to distill spentregenerant solution or other waste liquids from the resin regenerationprocess to recover distilled water;

FIG. 10B is a schematic side view of the thermal distiller of FIG. 10Aand a pumping system;

FIG. 10C is a schematic top view of the thermal distiller of FIGS. 10Aand 10B showing piping connecting an exhaust of an engine to the heatexchanger of the thermal distiller;

FIG. 11A is a schematic cross-sectional diagram showing treatedregenerant liquid being passed through a particle filter comprising ananofilter membrane;

FIG. 11B is a schematic perspective diagram of the nanofilter membraneof FIG. 11A; and

FIG. 12 is a pie chart showing the chemical composition of precipitatedcompounds of filter cakes generated by passing treated regenerant liquidthrough a filter press.

DESCRIPTION

An exemplary embodiment of a process for removing ions from a fluidusing an ion exchange resin, regenerating the spent resin with aregenerant solution, and recovering and recycling the spent regenerantsolution, is illustrated in the flowchart of FIG. 1. While an exemplaryembodiments of ion exchange apparatus, regeneration and recovery systemsand processes are illustrated herein, it should be understood that thepresent apparatus and process can be adapted for other apparatus andapplications as would be apparent to those of ordinary skill in the art,and that all such apparatus and applications are included in the scopeof the present invention.

In an ion exchange process, fluid is passed across ion exchange resin toremove ions from the fluid by exchanging the ions in the fluid withother ions in the ion exchange resin until the resin is spent, as shownin step 10 of FIG. 1. An exemplary ion exchange apparatus 20 to treat afluid, such as a liquid (e.g., water) containing ions by passing thefluid across ion exchange resin 22 to treat the liquid is shown in FIG.2. The ion exchange resin 22 removes some charged ions from the liquidby exchanging them for an equivalent amount of other charged ions in areversible chemical reaction. The ion exchange resins 22 can be in theform of resin beads 24, which partially fill a column 25 in acylindrical tank 26. The column 25 can include other purification andconditioning materials such as an activated carbon layer 27 to removeorganic contaminants from water, such as organic molecules, which areoften responsible for taste, odor, color problems, chlorine, and otherions and molecules. A permeation layer 28, such as a layer of gravel (asshown) or a wedge-shaped wire structure (not shown), at the bottom ofthe column 25 has perforations that are sized to allow treated liquid 45to leave the vessel while retaining the resin 22 and resin fines in thetank 26. Resin fines are caused by wear and tear attributed by normalservice life and regeneration and enhance the ion exchange process. Thepermeation layer 28 can be made, for example, from aluminum oxide orgarnet beads. A suitable wedge-shape wire structure can be made from,for example, a polymer such as polyvinyl chloride; a metal such asstainless steel; or combinations of the same, which does not degrade orleach chemicals into the treated water solution. A sieve 50 can beprovided to retain the permeation layer 28 while allowing treated waterto exit the permeation layer 28.

The tank 26 also has a top portion 40 with a liquid distributor inlet 44that is shaped and configured with holes 46 to distribute untreatedliquid 42 across the top cross-sectional area 48 of the tank 26. Thedistributed untreated liquid 42 is filtered and treated as it flowsthrough the column 25, under gravity or pressure from the top portion 40to the bottom portion 49 of the tank 26 to form treated liquid 45 at thebottom portion 49. The treated liquid 45 passes through the permeationlayer 28 and sieve 50 and into an outlet tube 47 which extends from thebottom portion 49 to, and out of, the top portion 40 of the tank 26 toexit the tank 26.

The ion exchange resin 22 can also have forms other than the resin beads24, such as ion exchange membranes, mesh, or other structures. The ionexchange resins 22 can also have different compositions depending on theion exchange application for which the resins are being used. In oneversion, the ion exchange resins 22 comprise an insoluble polymer matrixwith attached functional groups containing mobile ions that areexchanged with ions from the liquid being treated. The ion exchangeresins 22 can include, for example, strong or weak acid functionalgroups to form cation exchange resins, or weak or strong base functionalgroups to form anion exchange resins. Suitable strong acid cationexchange resins typically comprise sulfonated copolymerizedstyrene-divinylbenzene products which are crosslinked to varying degreesand are often used in water conditioning, demineralization of sugar andcorn syrups, chromatographic separations, and metal recovery. Suitableweak acid cation exchange resins can have functional groups comprisingphenolic, phosphorous or carboxylic entities, or combinations of theseor other groups, and such resins are used for water conditioning,chromatographic separation, and metal recovery. Strong base anionexchange resins can comprise quaternary ammonium groups in a polystyrenedivinylbenzene matrix, and are principally used in water conditioning.Weak base anion exchange resins contain primary, secondary or tertiaryamine groups, and mixtures thereof; they are available in a variety oftypes, including condensation products of amines with formaldehyde,alkyl dihalide, and chloromethylated styrene-divinylbenzene, and areoften used to demineralize corn syrups and corn sugar.

In one exemplary embodiment, an ion exchange resin 22 for treating waterto soften the water by removing divalent ions such as calcium,magnesium, barium, strontium and other such ions, comprises a cationexchange resin such as IONAC cationic resin, for example, the IONICC249™, fabricated by Sybron Chemicals Inc. Birmingham, New Jersey. Forexample, well or tap water can be treated to remove divalent ions suchas Ca⁺², Mg⁺², and SO₄ ⁻² ions from the water, and later exchange theremove ions for Na⁺ ions from the fresh resin 22 to give better qualitywater.

Optionally, the apparatus 20 can also include an ion exchange controller30 which controls a valve system 32 connected to the liquid distributorinlet 44 and the top of the outlet tube 52 to control the flow ofuntreated liquid 42 and treated liquid 45 in and out of the apparatus20. The controller 30 comprises programmable electronics and hardware tosend signals to control the valve system 32. For example, the controller30 can open an inlet valve 34 to allow untreated liquid 42 to filteredliquid into the column 25 of the tank 26 until the tank 26 is full ofwater, and at that time, shut the inlet valve 34. As another example,the controller 30 can also open an outlet valve 36 to release treatedliquid 45 as needed. The controller 30 can also operate the valve system32 to pass a regenerant solution through the ion exchange resin 22 whenthe resin become spent or trigger an LED light 38 or other alarm systemthat indicates when the resin is spent. The controller 30 can operatethe LED light 38 trigger in relation to the number of gallons ofuntreated liquid 42 that is passed through the column 25, the number ofwater treatment cycles, or simply a clock (not shown) that counts theoperational time since the last replacement of the resin 22. After anumber of liquid treatment cycles, the resin 22 become spent andsaturated with ions extracted from the liquid and also lose theirexchange efficiency from plugging up by solids. When the controller 30signals that the resin 22 has become, or is estimated to become, spentresin, the controller 30 signals the same for an operator to remove thetank 26 and replaces the spent resin tank with a new tank containingfresh resin 22.

Resin Regeneration and Recovery System I

Spent resin 60 extracted from a single or a plurality of ion exchangeapparatus 20 is regenerated by passing regenerant solution 186 acrossthe spent resin 60 in a resin regeneration and recovery system 80.First, the spent resin 60 is transferred out of the tanks 26 of a numberof different ion exchange apparatus 20 (such as small household ionexchange apparatus or large-scale ion exchange apparatus, such as thoseused in hotels, restaurants, and hospitals), and into a resinregeneration and recovery system 80, as shown in step 11 of FIG. 1.

An exemplary embodiment of a resin regeneration and recovery system 80to process spent resin 60 comprising spent cation exchange resin beads24, is illustrated in FIGS. 3A and 3B. Individual tanks 26 of ionexchange apparatus 20 are removed from small or large scale waterpurification sites after the resin is exhausted, and each tank 26 ofspent resin 60 is exchanged with a fresh resin tank. The spent resintanks 26 are transported to the regeneration facility by a truck 103.Each individual tank 26 of spent resin 60 is off-loaded from the truck103, positioned around the resin holding pit 102, and tipped upside-downto allow the spent resin 60 to evacuate out of the tank 26. The resinholding pit 102 can be a sub-grade pit or below ground level relative tothe street level.

A water jet nozzle 104 made of flexible copper tubing, is used to flushout the spent resin 60 from the tanks 26. The water jet nozzle 104 isconnected to a city water supply 108 or other source of pressurizedwater, such as a washout water tank 110 which holds recycled washoutwater 112 retrieved from washing out the tanks 26. The washout orpressurized city water is pumped to the water jet nozzle 104 by awashout pump 124 (which can be a centrifugal pump) in a water recyclingloop. A pressure gauge 118 on the pump 67 continuously monitors and setsthe pressure of the washout water 112 sent to the water jet nozzle 104.Excess washout water 112 recovered from the resin holding pit 102 viathe resin holding pit outlet 120 is first passed to a washout water sump122 where it is held until the water needed in the washout water tank110, at which time, it is pumped to the tank 110 with a submersiblewashout water pump 124 in the sump 122.

The spent resin 60 suspended in water is transferred to one or moreregeneration vats 140 a-c with a non-abrasive resin transfer pump 130 a.In the resin regeneration and recovery system 80, the spent resin 60 istransferred from the resin holding pit 102 to other vats and/or tanksusing non-abrasive resin transfer pump 130 a. A non-abrasive resintransfer pump 130 b can also be used to transfer the regenerated resingenerated from the present resin regeneration process. Advantageously,the non-abrasive resin transfer pumps 130 a,b have moving pumpingcomponents that can pump resin without excessively abrading, deforming,or re-shaping the resin. Suitable versions of non-abrasive resintransfer pumps 130 a,b and the resin-liquid mixture made fortransferring resin are described below.

In the spent resin transfer process, a suction port 132 of thenon-abrasive resin transfer pump 130 a is fluidly connected through aflexible hose or pipe to the spent resin 60 in the resin holding pit 102and an output port 134 of the pump 130 a is connected to a vat resininlet 136 a-c of the regeneration vats 140 a-c to transfer the spentresin 60 to the regeneration vats 140 a-c. The vat resin inlets 136 a-care located in upper vat regions 138 a-c of the vats 140 a-c so that thespent resin 60 can flow into the vats 140 a-c without draining anyresidual resin or water remaining in the vats. Also, the downward resinflow limits further damage to the spent resin 60 in the transferprocess. In one version, the vat resin inlets 136 a-c are located in thetop 30% volume as measured from the top of the vats 140 a-c.

In the embodiment illustrated, three regeneration vats 140 a-c areshown; however, there may be only one vat or more than three vatsdepending on the volume of spent resin 60 to be regenerated. While afirst vat 140 a is filled with a first volume of spent resin 60 and thentreated, a second vat 140 b can be filled with a second volume ofadditional spent resin 60, and so on. The desired volume of resin istransferred into any one of the vats 140 a-c, and the volume of resintransferred can be verified by an operator viewing through a sight glasswindow (not shown) on the side of the vats 140 a-c. The regenerationvats 140 a-c can be cylindrical tanks of steel plastic, or fiberglass,and they can be pressurized or open to the atmosphere. Alternatively,the regeneration vats 140 a-c can be partially or entirely made fromtranslucent polypropylene so that an operator can physically see thelevel of resin through the vat walls and turn off the resin transferpump 130 when a vat is filled.

After the desired volume of spent resin 60 is loaded into any one or allof the regeneration vats 140 a-c, the spent resin 60 is backwashed, asby step 12 of FIG. 1, by flowing backwash water 144 upward through thevolume of spent resin 60, for example, as shown in the vat 140 a, toremove suspended solids and particulates that would otherwise interferewith the efficiency of the resin regeneration process. Referring to FIG.3A, the regeneration vat 140 a is illustrated as being filled with spentresin 60 which is being backwashed with backwash water 144; however, thebackwash process can be performed in any of the vats 140 a-c. Thebackwash water 144 flows into the vat 140 a through a set of backwashnozzles 148 a-c located at the bottom of the vat 140 a. For example, thebackwash nozzles 148 a-c can be a series of linear apertures at thebottom of the vats 140 a-c which are sized and configured to promoteeven flow dispersion through the resin bed. The linear apertures can beelongated rectangles with square or arcuate corners. The linearapertures can also be covered with a screen having holes smaller thanthat of the smallest resin beads to allow the filtered backwash water144 from the backwash recovery system to be introduced into the vats 140a-c without resin beads 24 flowing back into the linear apertures toescape the vat during the down flow of liquids in the vat.

A backwash supply tank 150 holds backwash water 144 which is cleanedprior to use for backwashing resin to avoid coating the spent resin 60with resin fines 166 or other colloidal or suspended particulates. Abackwash recovery pump 160 delivers backwash water 144 from the backwashsupply tank 150 to any of the vats 140 a-c at a flow rate and durationsufficiently low to prevent over-liquidization of the volume of spentresin 60 in the vats 140 a-c. Typically, a resin bed expansion fromabout 50% to about 75%, which correlates to from about 5-gpm/ft² toabout 6.5-gpm/ft² hydraulic loading rate, is used to effectively removethe solids accumulated on the spent resin 60. The regeneration vats 140a-c are sized wide enough in diameter to ensure proper hydraulic loadingrates (gpm/ft²), and tall enough to allow ample headspace for expansionof the bed of spent resin 60. If sized properly, only the resin fines166, which are produced from normal wear and tear over the resin life,are lifted from the resin bed and escape from the upper vat region 138a-c of the regeneration vats 140 a-c. In one version, the backwashrecovery pump 160 has a variable frequency drive that receives a signalfrom a flow meter to speed up or down to maintain a pre-set flow ratethat correlates to the previously mentioned hydraulic loading rates,depending on the hydraulic losses through the filter and different flowpaths to the vats 140 a-c.

After backwashing the spent resin 60, the backwash water 144 is sent toa backwash settling tank 164 to capture resin fines 166 that escaped theregeneration vat 140 during the backwash process. The resin fines 166are retained for mixing with the regenerated resin 194 as they have highsoftening capacity due to the high surface area to volume ratio. Theresin fines 166 accumulate at the bottom of the backwash settling tank164 and are extracted from there via the backwash settling tank outlet168. The backwash settling tank 164 can be a cylindrical tank with aconical bottom (not shown) to facilitate collection of the resin fines166 from the bottom of the tank by gravity. The resin fines 166 can alsobe collected by suction with a non-abrasive resin transfer pump 130. Thebackwash settling tank 164 can also be made of a translucent material toallow the level of the resin fines 166 to be easily determined so thatthe resin fines can be removed from the bottom of the backwash settlingtank 164 before they accumulate to reach the level of the backwashsettling tank intake 170, which is typically a few feet from the bottomof the backwash settling tank 164. The resin fines 166 are reintroducedto the regeneration vats 140 a-c after backwashing of the spent resin 60in the vats 140 a-c is completed and before the resin regenerationprocess is started to allow the resin fines 166 to be thoroughly remixedwith the remaining spent resin 60. If the resin fines 166 are notdispersed thoroughly with the other spent resin 60, it is possible thatan individual tank 26 of resin at a customer site will have too manyresin fines 166 which can cause excessive headloss and pressure problemsfor the ion exchange apparatus 20 operating with the regenerated resins194.

The supernatant of the backwash settling tank 164 is pumped through abackwash particle filter 184 via the backwash pump 160, either before abackwashing process is conducted or at the time the backwashing processis conducted. After filtering through the backwash particle filter 184,the cleaned backwash water 144 is transferred to the backwash supplytank 150. Periodically, either softened city water can be added to thebackwash supply tank 150 to augment the water lost in backwashing, orexcess backwash water 144 can be sent to a backwash water sump 178 usinga backwash supply tank outlet 180 or sent back to the tank 150 when thebackwash water level is low using backwash sump pump 182, which can be asubmersible pump.

The backwash water 144 is cleaned before or after the backwashingprocess by filtering the backwash water 144 through a backwash particlefilter 184 which uses a fine cloth or other structure to filter outparticles. A suitable backwash particle filter 184 is a diatomaceousearth filter, cartridge filter, bag filter, microfiltration ornanofiltration membrane. In one version, the diatomaceous earth filtercomprises a plurality of cartridge filters arranged in a revolverconfiguration, each of which is coated with the diatomaceous earthmaterial which is a naturally occurring, soft, siliceous sedimentaryrock powder having a particle size of from about 1 micron to about 1 mm,or even from about 10 to about 500 microns. The cartridge filter acts asan underlying drain to support the filter media. A suitable cartridgefilter comprises a mesh size of from about 0.1 to about 100 microns, oreven less than 10 microns, or even about 5 microns. When a diatomaceousearth filter is used, the media of the cartridge filter is backwashedwhen the pressure differential across the filter reaches 10 psi.Additional diatomaceous earth material is needed to recoat the filterbag after every backwash cycle per manufacturer suggestions. A suitablediatomaceous earth filter comprises a QUAD DE 100 filter fabricated byPentair, Inc. Minneapolis, Minn. Alternatively, if a microfiltrationmembrane is used, the membrane is cleaned when the trans-membranepressure exceeds the manufacturer recommendations by back-flushing themembrane with water in a pulsed flow, followed by air scouring.

After the spent resin 60 is backwashed in the regeneration vats 140 a-cto remove particulates and solids, the spent resin 60 can be treatedwith regenerant solution 186, as in step 13 of FIG. 1. Initially, afirst batch of fresh regenerant solution 186 is made and stored in aregenerant solution tank 188, which also serves as the tank forreceiving recovered regenerant solution 186. The composition of theregenerant solution 186 depends on the composition of the spent resin 60and the type of ions accumulated in the spent resin 60. In the exampleprovided above, the cation exchange resins 22 accumulate divalent ions,such as calcium, magnesium and other ions, when used to treat hard waterto obtain soft water. Such spent resin 60 can be regenerated using aregenerant solution 186 comprising a solution of sodium ions andchloride ions, e.g., obtained from brine which is sodium chloridedissolved in water. The water can be ordinary tap water, or can bepurified water, such as distilled water. In one version, the brinesolution contains sodium chloride dissolved in water in a weight percentconcentration of from about 5 wt % to about 26 wt %, or even from about10 wt % to about 15 wt %. In an exemplary version, a regenerant solution186 comprising a salt concentration of 13% by weight, and made bydissolving 1797 pounds of sodium chloride in 1508 gallons of water, canbe used to regenerate 120 cubic feet of spent resin 60 at a dosage of 15pounds of salt per cubic foot of spent resin. The regenerant solution186 comprising a brine solution of sodium chloride dissolved in water isuseful for treating cationic exchange resins such as, for example, IONACC-249 manufactured by SYBRON Chemicals. IONAC C-249 is an ion exchangeresin 22 in the form of beads comprising crosslinked, polystyrenesulfonate cationic ion exchange resin and having bead sizes ranging fromabout 0.4 mm to about 1.2 mm.

Alternative types of regenerant solution 186 can be used depending onthe composition of the ion exchange resin 22 being regenerated and theions which need to be replaced from the ion exchange resin 22. Forexample, a regenerant solution 186 useful for regenerating an anionresin can include sodium or calcium hydroxide dissolved in water insufficiently high concentration to regenerate the ion exchange capacityof the anion exchange resin. As another example, anion exchange resins,particularly weak base anion resins, can be used for some industrialwater treatment processes, for example, to remove nitrates from water.Anion exchange resins are also be used to deionize water, such as insemiconductor manufacturing processes, which use a hydroxidepre-saturant ion and generate a brine solution that has a relativelyhigh concentration of chloride ions. Chloride ions, as well as othercommon anions such as sulfate, carbonate, bicarbonate, nitrate, nitrite,and fluoride ions, can precipitate at low concentrations by treatmentwith a regenerant solution 186 comprising a heavy metal ion (e.g., lead,copper, barium). In these applications, the regenerant treatmentcomposition 111 can include soluble ions of a heavy metal, which whenmixed with the regenerant solution can precipitate the compoundscontaining the chloride, sulfate, carbonate, bicarbonate, nitrate,nitrite, and fluoride ions.

The regenerant solution 186 from a regenerant solution tank 188 ispumped using a regenerant solution pump 190 and dispersed in theregeneration vats 140 a-c in a continuous flow via the overhead vatinlets 192 a-c to provide flow dispersion across the surfaces of thespent resin 60. In FIG. 3A, the regeneration vat 140 b is shown forillustration as containing spent resin 60 being treated with regenerantsolution 186 to regenerate the spent resin 60; however, the regenerationprocess can be performed in any of the vats 140 a-c.

Regenerant solution 186 is flowed through the spent resin 60 forsufficient time to regenerate the spent resin 60 to form regeneratedresin 194, as in step 14, and spent regenerant solution as in step 15,of FIG. 1. The regenerated resin 194 has substantially the same ionconcentrations as the fresh ion exchange resin 22, for example, an ionconcentration difference of ±5% wt %. In one version, the regenerantsolution 186 is passed through the vats 140 a-c until the spent resin 60is exposed to a total volume of regenerant solution in a volumetricratio of spent resin to regenerant solution of from about 0.5:1 to about2:1, or even 1:1. For example, a 1 liter volume of spent resin 60comprising cation exchange resins can be exposed to a total volume ofregenerant solution 186 of also about 1 liter. In one example, theregenerant solution 186 having the concentrations described above ispassed through the regeneration vats 140 a-c in a continuous flow for atleast about 5 minutes or even from about 10 minutes to about 30 minutes,to regenerate the spent resin 60 to form regenerated resin 194. Theregeneration process can be terminated after a fixed time, or usingsalometer readings in the regenerant vat drain line 200 a-c whichindicate that the spent regenerant solution 100 being released from theregeneration vats 140 a-c no longer changes in salinity or other levels.At this time the remaining regenerant solution 186 passing through anyof the vats 140 a-c can be diverted directly to the regenerant solutiontank 188 as this solution does not need to be recovered.

After the resin regeneration process, the regenerated resin 194 isrinsed as shown in step 16 of FIG. 1. The first two-thirds of the rinsevolume (as shown in step 19 of FIG. 1) is diverted to the regenerantrecovery system 205 for treatment as it has high salinity and hardness.In the rinsing step, which is shown for illustration as being performedin regeneration vat 140 c in FIG. 3A but which can be performed in anyof the vats 140 a-c, rinse water 196 is pumped from a rinse water tank198 through the regenerated resin 194 in any of regeneration vats 140a-c to rinse out regenerant solution 186 left on the regenerated resin194. The rinse procedure is stopped after the proper volume of soft,non-saline rinse water 196 is passed through the regenerated resin 194,which can be determined when a conductivity meter 225 or salometer,which is mounted on the regeneration vat drain lines 200 a-c andmeasures the spent rinse water 204 as it passes through the regenerationvat drain lines 200 a-c, give readings that are substantially the sameas (e.g., ±5%) the readings on fresh rinse water 196. In one version,about 50 to 100 gallons of rinse water 196 are used to remove most ofthe regenerant solution 186 and associated compounds (e.g., salt) fromthe regenerated resin 194. This amount of spent rinse water 204 can bediverted to the regenerant solution tank 188 as it has a largeconcentration of regenerant compound. After this time, another 300 to600 gallons of water is used to further clean the regenerated resins194, and this volume is sent to a salt water sump 197 (or a regenerantwaste liquid sump 214, for possible recovery as regenerant solution 186.Thereafter, any additional rinse water 196 passing through the resin inthe vats 140 a-c, which is clean by now, is passed to the spent rinsewater sump 202 for reuse rinsing additional regenerated resin 194 aftersuitable treatment. The spent rinse water 204 drained into the spentrinse water sump 202 is pumped by a submersible pump 206 to theregenerant recovery system 205, thermal distiller 420, or sewer system.The submersible pump 206 in the spent rinse water sump 202 is turned onwhen a float switch 208 indicates a high water level and continues topump until the level in the sump 202 becomes a low water level.

After the regeneration process, the regenerated resin 194 is transferredto a regenerated resin tank 95 via vat resin outlets 98 a-c of theregeneration vats 140 a-c, respectively, each of which can also have vatresin valves 99 a-c that open when the resin has completed regenerationand rinsing. The regenerated resin 194 is pumped out of the regenerationvats 140 a-c using the resin transfer pump 130 b with the appropriateplumbing lines. The regenerated resin 194 is reused in ion exchangeapparatus 20 by refilling the tanks 26 of the ion exchange apparatuswith the regenerated resin 194.

The resin regeneration and recovery system 80 treats spent regenerantsolution 100, as shown in step 17 of FIG. 1, in a multi-step process torecover and recycle the regenerant solution 186. The regenerationprocess creates spent regenerant solution 100 comprising brine and thedivalent ions removed from the spent resins 60. In conventionalprocesses, the spent regenerant solution 100 was typically flushed outinto the municipal water or sewage systems. Consequently, a large volumeof spent regenerant solution 100 containing undesirable compounds waspassed to the drainage system. This creates an environmental problem,generates a lot of wastewater, and is costly because a large volume ofwater is used to create new regenerant solution 186 as well as largeamounts of sodium chloride or other compounds, all of which are wastedwith each regeneration treatment cycle. In contrast, the recovered,purified regenerant solution 186 can be reused, by itself or withadditional water or chemical compounds, to treat additional spent resin60. The regenerant recovery process reduces the amount of regenerantsolution 186 and salt needed to be discarded after an ion exchange resinregeneration process. This is good for the environment, reducesregeneration costs, and can even allow reuse of the compounds formed inthe extraction of ions from the spent regenerant solution 100.

The spent regenerant solution 100 comprises different ions in varyingconcentrations depending on the nature of the ion exchange resins 22,the composition of the liquid being treated, and the ions removed fromthe liquids by the resins 22. For example, regenerant solution 186comprising a brine solution can be used to treat spent ion exchangeresins 22 which were used to remove multivalent ions 424 from water. Theresultant spent regenerant solution 100 can contain (i) primaryexchanging ions such as monovalent sodium ions which are used in thebrine solution, (ii) secondary exchanged ions removed from the spentresin 60 such as divalent ions, e.g., calcium ions, magnesium ions, andother types of ions, in smaller concentrations, and (iii) solids removedfrom the spent resins 60. For example, the spent regenerant solution 100can have a hardness of greater than 15,000 mg/L as CaCO₃, or even 40,000mg/L as CaCO₃, depending on the amount of spent resin 60 beingregenerated at a time and the amount of spent resin 60 that is fullyexhausted. As another example, the spent regenerant solution 100 canhave a salinity concentration of from about 10% to about 15% by weight.Thus, treatment of the regenerant solution 186 depends on the chemicalcomposition of the solution at the time the regenerant solution 186 isextracted from the recovery system for treatment.

Referring back to FIG. 3A, the spent regenerant solution 100 istransferred from the regeneration vats 140 a-c via the vat solutionoutlets 106 a-c controlled by vat solution valves 105 a-c to aregenerant waste liquid sump 214. For the sake of simplicity in thefollowing description, spent regenerant solution 100 refers to spentregenerant solution by itself or a combination of spent regenerantsolution and other types of regeneration waste liquids. The sump 214collects the spent regenerant solution 100 and/or other salt containingwaste liquids, such as an initial amount of spent rinse water, until itfills up, or there is enough spent regenerant solution 100 for a batchtype regenerant recovery process. The spent regenerant solution 100 isthen pumped from the regenerant waste liquid sump 214 using a spentregenerant pump 219, which can be a submersible pump or a centrifugalpump, to a spent regenerant tank 220 which is used to store the spentregenerant solution 100 until the regenerant recovery system 205 is tobe operated. Spent regenerant solution 100 is pumped from the spentregenerant tank 220 to the regenerant recovery system 205 for treatmentand recovery of the spent regenerant solution 100.

The portion of the resin regenerant and recovery system 80 used fortreating spent regenerant solution 100 with a regeneration treatmentcomposition 111 (as per step 17 of FIG. 1) is illustrated in FIG. 3B. Inoperation, the spent regenerant solution 100 is pumped to the inlet 109a of the regenerant recovery tank 296 using a regenerant solution pump203 which can be a centrifugal pump. At this time, a sample of the spentregenerant solution 100 is drained off the pipeline and collected in thesample jar for analysis. The regenerant solution sample should be filledat the same rate of flow as the flow rate of spent regenerant solution100 into the regenerant recovery tank 296 to get an accurate,representative water sample. The sample solution is chemically analyzedto determine the concentrations of different ions and compounds, suchas, for example, any of magnesium, calcium, sodium, chlorine, and so on.The chemical analysis is then used to determine the composition of theregenerant treatment composition 111 that is used to regenerate thespent regenerant solution 100.

In one version, the spent regenerant solution 100 comprises a solutionof sodium ions and chloride ions, for example, obtained from sodiumchloride dissolved in water and which has dissolved divalent ions, suchas calcium, magnesium, barium and other ions. A regenerant treatmentcomposition 111 suitable to treat this composition of spent regenerantsolution 100 comprises (i) a hydroxide component, comprising one or morehydroxide compounds, to remove soluble ions from the spent regenerantsolution 100 that form precipitate flocs 114 containing hydroxidecompounds, and (ii) a carbonate component, comprising one or morecarbonate compounds, to remove soluble ions from the spent regenerantsolution 100 that form precipitate flocs 114 containing carbonatecompounds. Suitable hydroxide compounds comprise calcium hydroxide,sodium hydroxide, or other alkali or alkaline earth metal hydroxides.Suitable carbonate compounds comprise sodium carbonate or other alkalior alkaline earth metal carbonates. The hydroxide component is added ina molar ratio of at least about 70 mM of hydroxide ions per liter ofspent regenerant solution 100, or even from about 30 to about 120 mM ofhydroxide ions per liter. The carbonate component is added in a molarratio of at least about 50 mM of carbonate ions per liter of spentregenerant solution 186, or even from about 60 to about 360 mM ofcarbonate per liter.

In one version, the regenerant treatment composition 111, used in step17, comprises a hydroxide component comprising a mixture of calciumhydroxide and sodium hydroxide, and a carbonate compound comprisingsodium carbonate. Advantageously, a mixture of calcium hydroxide andsodium hydroxide not only precipitates compounds from the spentregenerant solution 100 but also serves to add sodium ions to replenishthe sodium ion concentration within the spent regenerant solution 100.The addition of sodium hydroxide assists in decreasing the sludge volumeby producing a denser sludge.

As one example, a suitable regenerant treatment composition 111 caninclude calcium hydroxide, sodium hydroxide, and sodium carbonate. Thecalcium and sodium hydroxide can be added in an amount sufficient toprecipitate at least about 90% of the magnesium ions in the spentregenerant solution 100 to form a first precipitate compound comprisingmagnesium hydroxide; and the sodium carbonate can be added in an amountsufficient to precipitate at least about 90% of the calcium ions in thespent regenerant solution 1000 to form a second precipitate compoundcomprising calcium carbonate. Precipitation of the calcium carbonate andmagnesium hydroxide removes most of the undesirable divalent ions in thespent regenerant solution 100.

The amount of the regenerant treatment composition 111 added to thespent regenerant solution 100 to remove all the mineral hardness isdetermined by the background or baseline total mineral hardness in mg/Las CaCO₃. The mineral hardness concentrations in spent regenerantsolution 100 used to regenerate a 120 cubic foot batch of spent resin 60can be from about 10,000 to about 50,000 mg/L as CaCO₃ depending on howexhausted the spent resin 60 is at the time of the regeneration.Assuming that the regenerant treatment composition 111 comprises 99%pure calcium hydroxide, sodium hydroxide and sodium carbonate, thefollowing dosages result in treated regenerant solution containing totalhardness levels less than 300 mg/L as CaCO₃.

For total hardness concentrations in the spent regenerant solution 100of from about 10,000 to about 25,000 mg/L as CaCO₃, 2,996 g/L calciumhydroxide or 40.43 moles/L calcium hydroxide: 0.2498 moles/L totalhardness as CaCO₃; 2,996 g/L sodium hydroxide or 75.91 moles/L sodiumhydroxide: 0.2498 moles/L total hardness as CaCO₃; and 23,968 g/L sodiumcarbonate or 226.1 moles/L sodium carbonate: 0.2498 moles/L totalhardness as CaCO₃.

For total hardness concentrations in the spent regenerant solution 100of from about 25,000 to about 35,000 mg/L as CaCO₃, 2,996 g/L calciumhydroxide or 40.43 moles/L calcium hydroxide: 0.3497 moles/L totalhardness as CaCO₃; 2,996 g/L sodium hydroxide or 75.91 moles/L sodiumhydroxide: 0.3497 moles/L total hardness as CaCO₃; and 29,960 g/L sodiumcarbonate or 282.7 moles/L sodium carbonate: 0.3497 moles/L totalhardness as CaCO₃.

For total hardness concentrations in the spent regenerant solution 100of from about 35,001 to 45,000 mg/L as CaCO₃, 2,996 g/L calciumhydroxide or 40.43 moles/L calcium hydroxide: 0.4496 moles/L totalhardness as CaCO₃; 2,996 g/L sodium hydroxide or 75.91 moles/L sodiumhydroxide: 0.4496 moles/L total hardness as CaCO₃; and 35,952 g/L sodiumcarbonate or 339.2 moles/L sodium carbonate: 0.4496 moles/L totalhardness as CaCO₃. This ratio provides the benefits of consistentremoval of the total hardness to less than 300 mg/L as CaCO3 while stillmaintaining the salinity, or salt concentration, of 10% to 13% byweight, required to regenerate subsequent spent cationic resin.

In the examples above, the chloride ion concentration in the treatedregenerant liquid 342 can be adjusted by adding a chloride ion source,such as hydrochloric acid, to the treated liquid 342. For example,between 8 gallons and 16 gallons of 31.5% hydrochloric acid per 1,000gallons of treated regenerant solution can be used to bring the pH downto an acceptable range of from about 6.5 to about 7.5.

The spent regenerant solution 100 in the regenerant recovery tank 296 isthen pumped through piping 334 in a continuous flow through a chemicaldispenser 280 into which a regeneration treatment composition 111 is fedfor mixing with the spent regenerant solution 100. A diaphragm pump 65is used to pump the spent regenerant solution 100 and from the bottom ofthe regenerant recovery tank 296 as the motive flow 55 for the chemicaladdition in the chemical dispenser 280. A peristaltic pump, similar tothe ones used for brining and resin transfer, can also be used as analternative method of pumping the chemically dosed, soft, spentregenerant solution 100 without shearing the flocs 114 formed in theliquid.

A regenerant treatment composition 111 comprising the desired weights orconcentrations of compounds capable of recovering the spent regenerantsolution 100 is dispensed into the spent regenerant solution. Forexample, the regenerant treatment composition 111 can include at leastone hydroxide component and at least one carbonate component which reactwith the regenerant solution to form treated regenerant liquid andprecipitate flocs 114. In one version, solids comprising the regeneranttreatment composition 111 are injected into the chemical dispenser 280while the spent regenerant solution 100 is flowed across the dispenser280 to achieve rapid mixing. In this step, a flow of spent regenerantsolution 100 from a recovery tank outlet 107 of the regenerant recoverytank 296 is pumped through the piping 334 with the valve 307 in an openposition using a diaphragm pump 65 so that a stream of spent regenerantsolution 100 mixes with the regenerant treatment composition 111dispensed from the chemical dispenser 280. The resultant solution streamcomprising the regenerant treatment composition 111 is then passed intothe second inlet 109 b which is at the top of the regenerant recoverytank 296 to complete a closed loop system that is open to theatmosphere.

In one version, the chemical dispenser 280 comprises a venturi mixer 281that includes a hopper 278 having a mixing well 282 for more efficientmixing of the regenerant treatment composition 111 into the spentregenerant solution 100, as shown in FIGS. 3B and 3C. The mixing well282 comprises a conical funnel 283 having a built-in water spraydispenser 286 comprising one or more wash-down nozzles 284 lining thefunnel 283. The spray dispenser 286 can be connected via side tubing 297to the main tube 299 that supplies liquid to the venturi mixer 281 toreceive an offshoot of the liquid flow as it travels through the tube299. The nozzles 284 of the spray dispenser 286 are oriented to sprayliquid or mist down the internal sides of the mixing well 282 in aspiral flow 291. The spiral flow 291 of a stream or mist of liquidreduces airborne particulate emissions to dissolve and dilute thechemicals of the regenerant treatment composition 111 added to themixing well 282 as the chemicals pass through the flow of spentregenerant solution 100. For example, the spray dispenser 286 can subduepowder fines from the hydroxide or carbonate compounds of the regeneranttreatment composition 111 that would otherwise become airborne upondispensing into the mixing well 282. The regenerant treatmentcomposition 111 is added in a solid form to mixing well 282 to reach theventuri mixer 281 and achieve rapid mixing into the passing flow ofspent regenerant solution 100 after passing through the venturi opening287 at the bottom of the mixing well 282, as shown in FIG. 3C.

Referring to FIG. 3C, the venturi mixer 281 can be an eductor 612 havinga pressure connection 618, a discharge connection 620, and one or moreregulators 622. An eductor hopper 615 is positioned between the pressureconnection 618 and the discharge connection 620, such that the hopper615 comprises an inlet 624 configured to receive chemicals of theregenerant treatment composition 111, and an outlet 630 to dispense thechemicals of the regenerant treatment composition 111 to the liquidstream passing though a liquids channel 640. The liquid channel 640passes a flowing stream of spent regenerant solution 100 past the outlet630 of the hopper 615 to receive, and disperse, the dispensed regeneranttreatment composition 111 into the flowing liquid stream. Thecomposition 111 is passed to the flowing stream as it flows through thepressure connection 618 and the discharge connection 620. Pressureconnection 618 and discharge connection 620 may be substantiallyintegrated into piping 334 that transfers the spent regenerant solution100 being treated in the regenerant recovery tank 296. The pressureconnection 618 provides a pressure differential in liquid as it flowsunder the eductor hopper 615 so as to force liquid to increase velocityor mix with the chemicals of the regenerant treatment composition 111,such as the hydroxide and carbonate chemicals, as they are introduced.It should be further appreciated that one or more regulators 622 may beimplemented to assist in regulation of flow of water to eductor 612 orto assist in creation of suction in the eductor hopper 615. One or morevalves 628 can also be used to assist in management of the pressureregulator 622. The venturi mixer 281 can achieve a mixing intensity ofapproximately 200 s⁻¹ and provides thorough chemical dispersion in thespent regenerant solution 100.

The chemical-laden spent regenerant solution 100 is pumped in a closedloop through the piping 334 back to the regenerant recovery tank 296 andagain through the chemical dispenser 280 to receive additionalregenerant treatment composition 111. This closed loop pumping system iscontinued by pumping using the diaphragm pump 65 until all of theregenerant treatment composition 111 has been added to the spentregenerant solution 100.

In the regenerant recovery tank 296, a circulation mixer 275, such asthe suspended impeller mixer 322 provides slow mixing of the spentregenerant solution 100 with the dispersed regenerant treatmentcomposition 111 to dissolve the chemical compounds and allow undesirableions in the spent regenerant solution 100 to precipitate out asprecipitated compounds in the spent regenerant solution 100 within thetank 296. The suspended impeller mixer 322 in the regenerant recoverytank 296 provides slow mixing to allow the precipitated compounds tocoalesce into precipitate flocs 114, for example, precipitated hydroxideor carbonate compounds. For example, a suitable slow mixing rate thatallows precipitate flocs 114 of the precipitated compounds to form inthe chemically-treated solution is from about 10 s⁻¹ (one rotation inabout 1/10 sec) to about 15 s⁻¹.

The precipitate flocs 114 formed in the spent regenerant solution 100are separated from the treated regenerant liquid 342, as per step 18 ofFIG. 1, to form a separated regenerant solution or supernatant, such as,for example, the filtered regenerant solution 374. In one version, theprecipitate flocs 114 formed in the spent regenerant solution 100 areseparated by passing the liquid through a solids separator 500 such as afiltering system 324, (e.g., a filter press or centrifuge). After theprecipitate flocs 114 being to be formed, the impeller mixer 322 in thetank 296 is stopped and the inlet valve 305 on the filter press 300 isopened while the bypass valve 307 is closed. This causes treatedregenerant liquid 342 (comprising spent regenerant solution 100 andprecipitated flocs 114) to flow through an intake 310 of the filteringsystem 324 and filtered regenerant solution 374 to begin flowing out ofthe outlets 311 a,b and the opened outlet valves 308 a,b. In oneversion, the filtering system 324 comprises a filter press 300 whichseparates the flocs of precipitated carbonate and hydroxide compoundswhile allowing filtered regenerant solution 374 to flow through thepress 300. A suitable filter press 300 provides filtration andseparation of particles sized from about 0.1 to about 100 microns, oreven from about 1 to about 20 microns (e.g., 5 micron).

The residue from the filter press 300 comprises solids generated in theform of the filter cakes 304 comprises precipitated compounds, includingprecipitated calcium carbonate and magnesium hydroxide. The filter cakes304 can be resold or disposed of, or transferred to and stored, in asolids disposal dump 346. For example, the filter cakes 304 can be usedas additives/by-products in the following for cement, the purificationof iron ore in blast furnace, drilling liquid in oil industry,seacrete/Biorock, which is a high strength concrete and coral, paintextender, plastic filler, powder used in microporous baby diaper film,chalk, product in adhesives and sealants, replacement of kaolin inproduction of glossy paper, bleaching solutions, non-hazardous alkali toneutralize acidic wastes, smoke suppressant, fire retardant, wastewatertreatment plant, odor control, and seeding agents. The filter cakes 304or precipitate flocs 114 can also be disposed of in a non-hazardouslandfill or used as a by-product in concrete aggregate, cement gypsum,and many other industries.

The supernatant or filtrate, namely the filtered regenerant solution374, from the filter press 300 is separated and passed to the regenerantrecovery tank 296 for reuse as per step 21 of FIG. 1. The filteredregenerant solution 374 is transferred via piping 334 and through openvalve 289 in a closed loop while valve 289 is closed, and the clarity ofthe filtrate liquid throughout this process is visually inspected. Oncethe filtrate clarifies to drinking water clarity, the valves 289 and 290are reset to close valve 289 and open valve 290 to allow all thefiltered liquid flow to enter the pH-adjusting tank 350. The filtered isnow pumped using the diaphragm pump 65 through the filter press 300,across valve 290, and into the pH-adjusting tank 350.

Thereafter, the pH of the filtered regenerant solution 374 is adjustedas per step 23 of FIG. 1, in the tank 350, by a pH adjuster 351 to setthe pH to the desired level. For example, the pH can be adjusted byadjusting the concentration of at least one of the sodium ions orchloride ions in the filtered regenerant solution to be substantiallythe same, for example, ±10%, or even ±5%, of the concentration of thesodium ions or chloride ions in fresh regenerant solution 186. The pH ofthe filtered regenerant solution 374 can be adjusted in the tank 350 bya pH adjuster 351 to set the pH to the desired level and to have asufficient number of chloride ions to balance the sodium ions from theadded sodium hydroxide of the regenerant treatment composition 111. Itshould be noted that the treated regenerant liquid 342 in the regenerantsolution tank 188 typically contains from about 10% to about 13% byweight sodium chloride.

In one version, the pH adjuster 351 comprises a chloride ion source thatis capable of supplying chloride ions, such as a chloride-containingcompound, e.g., a chloride-containing acid such as hydrochloric acid.The hydrochloric acid is stored in a pH-adjuster tank 387 which canserve as an acid source tank, which is pumped using a pH-adjuster feedpump 389 (or a chloride ion adjusting pump) to an inlet 392 of the tank350. The pH adjuster 351 comprising the chloride ion compound is addedto the separated regenerant solution 374 to change the pH of thesolution. The pH of the regenerant solution can be adjusted to be withina value that is within about, ±10%, or even ±5%, of the pH of the freshregenerant solution 186. In one example, the chloride-containingcompound can be added to the separated regenerant solution 374 in avolume sufficiently high to adjust the pH of the separated regenerantsolution 374 to be in the acceptable range of from about 6.5 to about7.5. The chloride-containing compound can also be added in a volumesufficient to obtain a chloride ion concentration in the separatedregenerant solution 374 that is within about ±10%, or even ±5%, of thechloride ion concentration in the fresh regenerant solution 186. Forexample, from about 8 gallons to about 16 gallons of 31.5% hydrochloricacid per 1,000 gallons of treated regenerant liquid 342 or separatedregenerant solution 374 can be added to the spent regenerant solution100 to bring the pH down to an acceptable range of from about 6.5 toabout 7.5.

An impeller mixer 394 is used to mix the hydrochloric acid into theseparated regenerant solution 374. An online pH meter 396 that iscontinually submersed in the solution in the pH-adjusting tank 350indicates the when the operator can de-energize the pH-adjuster feedpump 389 when the pH falls with the desired neutral range. As analternative, periodic grab samples can be taken from the pH adjustingtank 350 to verify when the feed pump 389 can be de-energized.

After adjusting the pH, the separated regenerant solution 374 becomes atreated regenerant liquid 342 which is ready to be recycled as freshregenerant solution 186, and consequently, pumped by the solutiontransfer pump 230 back to the regenerant solution tank 188. The treatedregenerant liquid 342 is recycled and recovered regenerant solution 186and is pumped by the regenerant solution pump 190 to the resinregeneration vats 140 a-c for treatment of additional batches of spentresin 60. Approximately 1/10^(th) to 1/15^(th) of the initial volume ofthe treated regenerant liquid 342 is left at the bottom of theregenerant recovery tank 296. The volume of precipitate flocs 114 inthis liquid acts as a seeding agent to provide nucleation sites for thenext batch of filtered regenerant solution 374 which is to be treated inthe regeneration treatment process.

The resin regeneration and recovery system 80 described above can bemanually operated or operated with one or more control devices 352and/or a system controller 348 which controls many operations, or evenall the operations, of the regenerant recovery process. An exemplaryembodiment of a system controller 348, as shown in FIG. 3D, can be asingle control device 352 or a set of control devices 352 a-i, such as aplurality of separate or individual control devices (e.g., packagedcontrol panels). The control devices 352 can include switches,programmable logic chips (PLC) 354, and/or hard wire relays 356, and canoperate independently or in conjunction with each other.

In one version, the systems controller 348 is a general purpose computer358 comprising a CPU 360 with memory 362 and an input device 364, whichreceives and sends signals to all of the devices of the system 80 tocontrol the devices or display their signals in a display 368. Thesystem controller 348 may be also used to display the status of: thedifferent processes of the resin regeneration and regenerant treatmentprocess; the volume of resin or liquid in any of the tanks, pits, orvats that are filled with fresh resin 22, spent resin 60, regeneratedresin 194, regenerant solution 186, rinse water 196, backwash water 144,spent regenerant solution 100, or other liquids; salinity or pH of thesolutions; soaking or flow time of any of the liquids through the spentresin 60; the volume or mass of chemicals being added to form theregenerant treatment composition; and other process functions. Thesystem controller 348 is programmed with program code 370 comprisingsuitable operating code instructions written in computer language suchas C++, assembly language or the like or even programmed directly into aprogrammable logic chip. The program code 370 is computer code orinstructions sets of code that operate valves, pumps, filters, levelindicators, chemical dispensers, hoppers, and other components of thesystem 80 to perform the process shown in FIG. 1. The program code 370accepts incoming signals comprising data or instructions from thesecomponents and also sends outgoing signals comprising instructions ordata to these devices. For example, the system controller 348 can beprogrammed to control the regenerant recovery process in the resinregeneration system 80, and accordingly, is connected to the variouspumps, valves, chemical dispensers, and other control systems of thesystem 80. The system controller 348 can also control these devices andcomponents, receive signals from them, and transmit signals from thedevices to one another or to an operator.

The resin regeneration and recovery system 80 described herein allowsrecovery of greater than 90%, or even 98%, of the spent regenerantsolution 100. This greatly reduces the environmental impact that wouldotherwise be caused by the disposal of these materials, especially whenthe regenerant solution 100 contains a large amount of sodium chloride.The resin regeneration and recovery system 80 also reduces waterconsumption and saves the cost of the chemical compounds used in therecycled regeneration solution 100, as they are retained in the solutionwhile undesirable ions are removed by the recovery process.

Batch-Type Regenerant System II

Another exemplary embodiment of a batch-type resin regeneration andrecovery process is illustrated in the flowcharts of FIGS. 4A to 4D. Theresin regeneration and recovery system 80 processes spent resin 60,comprising spent cation exchange resin bead, from the tanks 26 of aplurality of ion exchange apparatus 20, as previously described. Theresin 60 is regenerated with regenerant solution 186 to form spentregenerant solution 100, which is treated and recovered for recycling inthe process by itself or mixed with other regenerant waste liquids suchas spent rinse water 204 or backwash water 144. Again, for the sake ofsimplicity, spent regenerant solution 100 refers to spent regenerantsolution by itself or a combination of spent regenerant solution 100 andother types of regeneration waste liquids. In one version, the system 80can, for example, be used to regenerate at least 3,000 gallons per dayof spent regenerant solution 100 per day; recover at least 2,000 gallonsper day of backwash water; and recover at least 1,800 gallons per day ofspent rinse water 204. This recovery process can substantially eliminatewaste regeneration liquids from resin regeneration and recovery process80 by giving a more environmentally friendly and cost-effective resinregeneration process.

A resin regeneration and recovery system 80 for regenerating spent resin60 according and recovering spent regenerant solution 100 is illustratedwith reference to FIGS. 5A to 5B. The spent resin 60 from a plurality oftanks 26 is transferred to one of the sub-grade resin holding pits 102a,b. A pair of pits 102 a,b can be used to allow shifting the receivinglocation of the spent resin 60 from a first resin holding pit 102 a to asecond resin holding pit 102 b. Each individual tank 26 is tipped toallow spent resin 60 to evacuate into one of the pits 102 a,b. The tank26 should not be filled with fresh resin 22 when dumping the spent resin60 into the resin holding pit 102 a. Additional tanks 26 are emptiedinto a first resin holding pit 102 a until the pit is filled to the topwith spent resin 60, at which time, any additional or leftover tanks 26are emptied into a second, standby resin holding pit 102 b.

A water jet nozzle 104 a,b is directed into the cavity of each tank 26to flush out spent resin 60 from the tanks 26 into the resin holdingpits 102 a,b using water from the washout sump 122 which is pumped witha washout water pump 124. The washout water pump 124 is energized whenthe water jet nozzles 104 a,b are opened and deenergizes when thenozzles are closed. To fill the washout sump 122, a backwash recoverypump 160 sucks dirty water from a backwash supply tank 150. Also, thefloor drain water overflows the dump pit and drains to the washout watersump 122 which is provided to hold non-salty water. From the washoutwater sump 122, the drain water can also be transferred to a backwashrecovery settling tank 164 or to the sewer using a drain pump 126.During spent resin dumping into the pits, a recirculation pump (notshown) which circulates water in the resin holding pit 102 should be instandby mode. The washout water pump 124 can also serve as therecirculation pump by pumping washout water from the sump 122 to theresin holding pits 102 a,b.

After a resin holding pit 102 a,b is filled with spent resin 60, a resindistribution manifold 165 is configured so that spent resin 60 can betransferred to a resin regeneration vat 140 a-c. A non-abrasive resintransfer pump 130 is used to transfer the spent resin 60 by connecting asuction port 132 of the pump 130 to the one of the resin holding pits102 a,b and an output port 134 of the pump 130 to one of the resinregeneration vats 140 a-c. A call to transfer the spent resin 60 from aresin holding pit 102 a,b to a regeneration vat 140 a-c can be initiatedmanually by activating the resin transfer pump 130 or via a command froma system controller 348, as previously described, which sends signals tothe resin distribution manifold 165.

In the pumping process, a liquid such as water is added to the spentresin 60 in the resin holding pits 102 a,b to form a liquid-resinmixture that facilitates pumping the resin between sites without havingto add a large amount of water to the resin. In one version, theliquid-resin mixture comprises a volumetric ratio of resin to water offrom about 0.5:1 to about 2:1. For example, to form liquid-resin mixturehaving a volumetric ratio of resin to water of about 1:1, one gallon ofwater is added for each gallon of resin to form the liquid-resin mixturein the pits 102 a,b. As compared to conventional centrifugal pumps, thenon-abrasive resin transfer pump 130 uses a ratio of resin to waterwhich reduces the amount of water required to transfer the resin by afactor of 10, or even a factor of 15. This substantially increases thespeed of resin transfer. Further, the non-abrasive resin transfer pump130 does not deform or otherwise change the resin bead shape and alsoreduces erosion of the resin and formation of resin fines 166 duringpumping operations. For this reason, the non-abrasive pump 130 isadvantageous compared to conventional centrifugal pumps.

The resin transfer process from a resin holding pit 102 a to aregeneration vat 140 a-c is stopped when a desired resin volume level isreached in a regeneration vat 140 a-c via a command from the controller348 to stop the resin transfer pump 130. The resin volume level can bedetermined from the fill height of the spent resin in the vat 140 a-cwhich is visually estimated through a sight glass or from asemi-transparent wall of the vat 140 a-c. In the transferring process,the spent resin 60 from the resin holding pit 102 a,b is sucked out viathe resin receiving pipes 292 a,b which terminates in the resin pitoutlets 96 a,b with resin tank valves 97 a,b, respectively, turned tothe “flow” position, to suction port 132 of the resin transfer pump 130.The pump 130 outputs the spent resin 60 through outlet port 134 to flowvia resin transfer pipe 294 to the vat resin inlets 136 a-c until one ormore of the vats 140 a-c are filled with spent resin 60. In the samemanner, spent resin 60 from resin holding pit 102 b can be sucked outvia the resin receiving pipe 292 b which terminates in a pit resinoutlet 96 b, with resin tank valve 97 b turned to the “flow” position.

After the desired volume of spent resin 60 is loaded into any one or allof the regeneration vats 140 a-c, the spent resin 60 is backwashed withbackwash water 144 in the vats 140 a-c to remove suspended solids andparticulates that would otherwise interfere with the efficiency of theresin regeneration process. The spent resin 60 is backwashed by passinga stream of water upwardly though the spent resin. In this step, the vatvalve manifold 199 is configured to allow backwash water 144 to fluidizethe spent resin 60 in the vat 140 a which is ready for backwashing. Thebackwash supply tank 150 holds clean or filtered water to be used as thebackwash water 144. The backwash water 144 is passed through the vat 140a to remove resin fines 166 and other colloidal and suspendedparticulates that would otherwise coat the spent resin 60 and reduce theefficiency of regenerating the resin. In the backwashing step, abackwash recovery pump 160 is energized to deliver clean or filteredbackwash water 144 from the backwash supply tank 150 at a flow rate andduration sufficiently low to prevent over-liquidization of the resin bed(volume of resin in tank) of spent resin 60 in the vats 140 a-c.Typically, a resin bed expansion from about 50% to about 75%, whichcorrelates to from about 5-gpm/ft² to about 6.5-gpm/ft² hydraulicloading rate, is used to effectively remove the solids accumulated onthe beads of spent resin 60. The regeneration vats 140 a-c are sizedwide enough in diameter to ensure proper hydraulic loading rates(gpm/ft²), and tall enough to allow ample headspace for expansion of thebed of spent resin 60. If sized properly, only the resin fines 166,which are produced from normal wear and tear over the resin life, arelifted from the bed and escape the top of the regeneration vats 140 a-c.

The resin fines 166 drawn out of the regeneration vats 140 a-c duringthe backwash process are recaptured by transferring the spent backwashwater 207 from the vats 140 a-c to a backwash settling tank 164. Theresin fines 166 accumulate at the bottom of the backwash settling tank164 and are extracted by opening a drain valve on a tank outlet 168before they accumulate to reach the level of the backwash settling tankintake 170, which is typically a few feet from the bottom of thebackwash settling tank 164. For a backwash settling tank 164 having aconical bottom, the resin fines 166 are evacuated using block and bleedvalves 172. The resin fines 166 can also be collected by suction with aventuri-injector or peristaltic pump. The resin fines are removed fromthe bottom of the backwash settling tank 164 and reintroduced to theregeneration vats 140 a-c after backwashing of the spent resin 60 in thevats 140 a-c and before the resin regeneration process to allow theresin fines 166 to be thoroughly remixed with the spent resin 60 as thefines have high softening capacity due to the high surface area tovolume ratio.

Recycled floor drain water can also be transferred by a backwashrecovery pump 160 to a backwash recovery tank. When there is enoughbackwash water 144 (or drain water) in the backwash supply tank 150,this dirty water is filtered and reused to backwash another batch ofspent resin 60 in a vat 140 a-c. In this process, the dirty water in thetank is pumped out by the backwash recovery pump 160, passed through aparticle filter 184 (as previously described), and then pumped into theregeneration vats 140 a-c to backwash the spent resin 60 in the vats ina closed loop configuration. In this step, the flow rate on the VFD 210is set to achieve the desired resin bed expansion in the vats 140 a-cand controlled by a signal from a backwash flowmeter 212. Typically, thesignal from a flowmeter 212 is at provided in a current range of fromabout 4 to about 20 mA. The backwashing step is completed when thebackwash water 144 overflowing from the vats 140 a-c has cleared upsufficiently as visible through a semi-transparent backwash overflowpipe, such as polyvinyl chloride (PVC) pipe. The filtered backwash water144 is transferred to the backwash supply tank 150 and stored in thetank or sent directly to another regeneration vat 140 a-c ready forbackwashing at the hydraulic fluid loading rate required to properlyliquidize the resin bed. Periodically, softened city water can be addedto the backwash supply tank 150 to augment the water lost in backwashingif a media or membrane system is used for filtration. The used orreclaimed water can also be removed after a period of time or when itreaches a threshold, such as a high bacteria count, undesirabledissolved material, or other factors.

After the spent resin 60 is backwashed in the regeneration vats 140 a-cto remove particulates and solids, the spent resin 60 is treated withregenerant solution 186. Initially, a first batch of regenerant solution186 is made having a concentration of sodium chloride in about 10 wt %to about 13 wt % in softened water and stored in a regenerant solutiontank 188. The regenerant solution 186 can be made adding sodium chlorideto water in a ratio of ½ volume of saturated brine solution with ½volume of softened water. The regenerant solution tank 188 also servesto store recovered regenerant solution 186. The composition of theregenerant solution 186 depends on the composition of the spent resin60, original resin 22, and the type of ions accumulated in the spentresin 60. In the example provided above, the cation exchange resinsaccumulate divalent ions, such as calcium, magnesium and other ions,when used to treat hard water to obtain soft water. Such spent resin 60can be regenerated using a regenerant solution 186 comprising sodiumchloride, that is, a brine solution of water with dissolved sodiumchloride. The water can be any hard water supply with total hardnesslevels above 140 mg/L as CaCO3.

The fresh or recovered regenerant solution 186 is pumped from the tank188 into one of the regeneration vats 140 a-c through the vat inlets 192a-c using a regenerant solution pump 190 as shown in FIG. 5B. Theregenerant solution pump 190 can be a positive displacement, peristalticpump, similar to the non-abrasive resin transfer pump but having avariable frequency drive device that ramps the rotation of the rollersup or down to maintain a consistent set flow rate as entered in the pumpdisplay by an operator. Since the volume of the regenerant solution 186in the hose of the peristaltic pump is constant, increasing ordecreasing the rotational speed of the rollers results in increasing ordecreasing the instantaneous flow rate. Advantageously, the chemicallycorrosive nature of the regenerant solution 186 comprising salt brinedoes not adversely affect the pump 190 since only the chemicallycompatible hose is in contact with the salt brine of the regenerantsolution 186.

An alternative regenerant solution pump 190 is a magnetic drivecentrifugal pump having a variable frequency drive (VFD) connected to aninternal or external programmable logic controller. A flow meteroutputting a signal of 4 to 20 mAmps is provided on the discharge of thepump to control the flow rate therethrough to the calculated flow rate.A programmable logic circuit (PLC) ramps up or down the speed of the VFDdepending on the desired flow rate and the signal from the downstreamflow meter. The magnetic drive pump has neodymium magnets that rotate aseal-less ceramic impeller in an enclosed volute. Such pumps are goodreplacements for mechanical sealed pumps in corrosive duty applications.Magnetic drive pumps can also achieve pump efficiencies of up to 70%,which results in significant savings of electricity. They also have veryhigh corrosion resistance since they are durably molded from corrosionresistant polypropylene or PVDF.

In the resin regeneration step, the vat valve manifold 199 is configuredto allow the regenerant solution 186 to flow through the spent resin 60for a sufficient time at a sufficiently high flow rate to regenerate thespent resin 60 into fresh resin 22. The desired time duration that theregenerant solution 186 is passed through the spent resin 60 in any ofthe vats 140 a-c is calculated and depends on the flow rate, percentageconcentration of salt in the regenerant solution, and the resin dosage.In an exemplary calculation for the flow duration with respect to flowrate, a one gallon volume of spent resin 60 comprising cation exchangeresins can be exposed to regenerant solution 186 comprising a salt brinesolution having sodium chloride in a strength of from about 10 wt % toabout 13 wt %, and a dosage rate of 10 pounds per cubic foot to 20pounds per cubic foot of resin. Household self-regenerating watersofteners can regenerate with lower brine concentrations with sodiumchloride concentrations of from about 4 wt % to about 8 wt %, and adosage rate of 4 pounds per cubic foot to 6 pounds per cubic foot ofresin. At a concentration of 10% by weight sodium chloride and a dosageof 20 pounds per cubic foot for a 120 cubic foot resin regeneration willresult in approximately 2,680 gallons of spent brine solution, or 22.3gallons per cubic foot of resin. At a concentration of 13% by weightsodium chloride and a dosage of 10 pounds per cubic foot for a 120 cubicfoot resin regeneration generates approximately 1,005 gallons of spentregenerant solution comprising brine, or 8.3 gallons per cubic foot ofresin.

While the examples provided herein are illustrated with respect to aregenerant solution 186 comprising a brine solution, other compositionsof regenerant solution 186, such as potassium chloride, can also be useddepending on the nature of the resins 22 and the desired water quality.The regenerant solution 186 is passed across the spent resin 60 forsufficient time and flow rate to regenerate the spent resin 60 to freshresin. For example, the regenerant solution 186 can be passed throughthe vat 140 in a co-current or countercurrent continuous manner at ahydraulic loading rate of 0.4 gallons per minute per square foot of vatsurface area to 4.0 gpm/ft2, until the desired volume of fresh brine, atthe previously stated concentrations, has been introduce to the resin 60in the vat 140.

Spent regenerant solution 100 flows out from the bottom of theregeneration vats 140 a-c via the vat solution outlets 106 a-ccontrolled by vat solution valves 105 a-c to a regenerant waste liquidsump 214 which collects the spent regenerant solution 100 until it fillsor there is enough spent regenerant for a regenerant recovery process.The spent regenerant solution 100 is then pumped from the regenerantwaste liquid sump 214 using a spent regenerant pump 219 (which can be asubmersible pump or a centrifugal pump) to a spent regenerant tank 220which is used to store the spent regenerant solution 100 until it ispumped to the regenerant recovery system 205 for treatment and recoveryof the spent regenerant solution 100.

It should be further noted that the first portion of the regenerantsolution 186 passing through the vats 140 a-c can be allowed to flowback to the backwash supply tank 150 until the measured total dissolvedsolids (TDS) in the outflow begins to rise up to levels higher than thecity water supply 108, as this portion represents flushed-out backwashwater 144 that can be reused for backwashing the resin. Thereafter, theremaining portions of the regenerant solution 186 comprises aconcentration of salt that is closer to that of fresh regenerantsolution, in addition to the ions extracted from the spent resin 60, andthis spent regenerant solution 100 is collected for treatment forrecovery and recycling as explained below.

The resin regeneration process is completed when a magnetic flow metertotalizer (not shown) on the pump 190 indicates a total flow ofregenerant solution 186 that passes through the pump which correspondsto the predetermined calculated volume of regenerant solution requiredto be passed through the resin bed in the regenerant vats 140 a-c toregenerate the spent resin 60. A suitable magnetic flow meter totalizerthat indicates instantaneous flow in gallons per minute and total flowin thousands of gallons comprises a PROMAG 53 manufactured byEndress+Hauser, Greenwood, Mass.

After performing the regeneration process, the regenerated resin 194 isrinsed with rinse water 196 at a predetermined or calculated flow rateto achieve exposure of the regenerated resin 194 to predetermined volumeof rinse water 196, the rinse water comprising softened or distilledwater. In the rinsing step, the vat valve manifold 199 and the mainwater distribution manifold 201 are configured to allow rinse water 196,comprising either soft filtered chlorinated rinse water or distilledwater from the thermal distillation recovery process, to enter theregeneration vats 140 a-c. The rinse water 196 enters the vats 140 a-cfrom the top vat inlets 192 a-c and exits from the bottom vat solutionoutlets 106 a-c by gravity where it flows past a salometer 221 and thenflows into the spent rinse water sump 202. During the rinsing process,the initial volume of spent rinse water 204 that passes across theregenerated resins 194 forces out a substantial quantity of theregenerant solution 186 comprising brine. Accordingly, this initialvolume of spent rinse water 204 has a high salt concentration and ispassed to the regenerant waste liquid sump 214. In the example providedabove, this initial volume of the salty spent rinse water 204 comprisestypically from about 50 to about 100 gallons. When the float switch 208of a submersible pump 206 in the spent rinse water sump 202, as shown inFIG. 5A, indicates that the sump 202 has been filled with rinse water196, the submersible pump 206 activates to pump the spent rinse water204 to the regenerant recovery tank 296 shown in FIG. 5B. Any residualportion of the rinse water 196 is then directed to a flow-monitoredsewer connection or to a thermal distiller 420 for distillation.

In the rinsing process, the proper volume of rinse water 196 should bepassed over the resin to thoroughly rinse the regenerated resin 194, andthis rinse end step can be determined when a conductivity or salometer221 on the vat drain line 200 indicates readings equal to those obtainedon fresh rinse water. For example, the resin rinsing process iscompleted when the salometer 221 on the drain line 200 of theregeneration vats 140 a-c indicates that the excess salt from theregenerant solution 186 has been substantially entirely rinsed off theregenerated resin 194. In this situation, the salometer 221 wouldindicate a low level of residual salt (for example, less than 0% byweight salt concentration, or 50 Mmho conductivity) in the flowing spentrinse water 204.

After the resin has been rinsed, the regenerated resin 194 istransferred out of the regeneration vat 140 using a resin transfer pump130 with the appropriate pipelines and isolation valves. In the resintransfer process, the resin distribution manifold 165 is configured topurge spent resin 60 into resin dump so as not to contaminateregenerated resin 194 that utilizes the same peristaltic pump and aportion of the main suction and discharge line.

At this stage, the regenerated resin 194 is fully rinsed off and readyfor reuse. The resin distribution manifold 165 is configured and theresin transfer pump 130 turned on to transfer the regenerated resin 194into the tanks 26 in the tank filling station 68. Thereafter, when thetanks 26 of the ion exchange apparatus 20 are ready to be filled withfreshly regenerated resin 194, the resin distribution manifold 165 isconfigured and the resin transfer pump 130 turned on to transfer theregenerated resin 194 into a plurality of individual tanks 26. After allof the regenerated resin 194 has been filled into a number of tanks 26,the tanks 26 are loaded onto a delivery truck 103 and delivered backinto ion exchange apparatus 20 in residential homes or offices.

As the regenerated resin 194 fills a tank 26 in the tank filling station68, residual rinse water that is softened water with a high totaldissolve solids content exits the tanks 26 and falls to the floor of thestation 68. Rubber stoppers in the floor drains which are connected to aresin dump pit 216 prevent the soft residual rinse water or regeneratedresin 194 from entering the resin dump pit 216. The carrier or resintransfer water, which is soft because it is the last water to havecontact with the regenerated resin 194 can be passed to the washoutwater sump 122. On completion of the tank filling operations, the pumps124 or 126 connected to the washout water sump 122 can be energized asthe water in the sump accumulates to a preset level to pump out water.

The resin regeneration process creates spent regenerant solution 100comprising brine containing the divalent ions removed from the spentresins 60. For example, after treating the spent cation exchange resins22, a regenerant solution 186 comprising a brine solution contains (i)monovalent ions such as sodium ions, (ii) divalent ions, such as calciumor magnesium ions, and (iii) solids removed from the spent resins, suchas resin fines 166, sand, and other particulates. In the presentprocesses, the spent regenerant solution 100 is regenerated and recycledinstead of being discarded. This avoids sending a large volume of spentregenerant solution 100 containing undesirable compounds, such as solidsand other metal ions such as calcium, magnesium and barium, to thesewage system. This, in turn, avoids increasing waste treatment andenvironmental problems while also saving a lot of water and largeamounts of sodium chloride. In addition, the regeneration and recyclingprocess for the spent regenerant solution 100 can also generatecompounds, such as calcium carbonate and magnesium hydroxide, which canbe recycled into other products. The present resin regeneration andrecovery system 80 allows treatment of the spent regenerant solution 100in a multi-step process to recover and recycle the regenerant solution186. The regeneration process creates spent regenerant solution 100comprising brine and the divalent ions removed from the spent resins 60.In conventional processes, the spent regenerant solution 100 wastypically flushed out into the municipal water or sewage systems.Consequently, a large volume of spent regenerant solution 100 containingundesirable compounds was passed to the municipal or private wastewatercollection system. This creates an environmental problem, generatingsignificant amounts of salt-laden wastewater with very high totalhardness levels. Such poor water quality cannot be removed economicallyin traditional activated sludge wastewater treatment plants and getspassed on to the end user of the treated wastewater. It is costly to theowner of the resin regeneration facility because often they are assessedimpact fees by the local wastewater treatment provider for the dischargeof this wastewater into their collection system, not to mention theyneed to continually purchase new water and salt for subsequentregenerations. In contrast, the recovered, purified regenerant solution186, as well as spent rinse water 204, can be reused, by itself or withadditional water or chemical compounds, to treat additional spent resin60. The regenerant recovery process reduces the amount of regenerantsolution 186 and salt needed to be discarded after an ion exchange resinregeneration process. This is good for the environment, reducesregeneration costs, and can even allow reuse of the solids generatedfrom the extraction of the ion in the spent regenerant solution 100.

The spent regenerant solution 100 or the regenerant waste liquid 376containing at least partially, the spent regenerant solution 100,comprises different ions in varying concentrations depending on thenature of the ion exchange resins 22, the composition of the liquidbeing treated and the ions removed from the liquids by the resins. Forexample, regenerant solution 186 comprising a brine solution can be usedto treat spent ion exchange resins which were used to remove polyvalentions from water. As before, the resultant spent regenerant solution 100can contain monovalent sodium ions which are used in the brine solution;polyvalent or divalent ions (e.g., calcium ions, magnesium ions, andother types of ions) in smaller concentrations; and solids removed fromthe spent resins 60. Thus treatment of the regenerant waste liquid 376or spent regenerant solution 100 depends on the chemical composition ofthe liquid 342 or solution 100 at the time they are extracted from therecovery system for treatment.

In the recycling process, spent regenerant solution 100 from each of theregeneration vats 140 a-c is transferred to a regenerant waste liquidsump 214 to form regenerant waste liquid 376 containing at leastpartially, the spent regenerant solution 100. The spent regenerantsolution 100 flows through the vat solution outlets 106 a-c and vatsolution valves 105 a-c which are located at the bottoms of theregeneration vats 140 a-c. In the treatment process, unwanted dissolvedand solids constituents are removed from the spent regenerant solution100 while leaving behind desirable compounds, such as sodium ions, toallow reuse of treated regenerant liquid 342. Optionally, other spent orwaste liquids from the resin regeneration process, such as, for example,spent backwash water 207, rinse water 196, and other liquids dischargedin the resin regeneration treatment process, can also be collected inthe regenerant waste liquid sump 214 and treated as a single compositionof spent regenerant solution 100. Other waste liquids are generallycollected only when these liquids have a high concentration of theresin-regenerant compounds, such as sodium chlorine or other salts. Itshould be understood that spent regenerant solution 100 is usedinterchangeably to mean either spent regenerant solution purely byitself, or spent regenerant solution combined with other waste liquids.Referring now to FIG. 5A, the regenerant waste liquid 376 containing atleast partially, the spent regenerant solution 100, is transferred fromthe regenerant waste liquid sump 214 via a submersible spent regenerantpump 219 to the spent regenerant tank 220. A suitable tank 220 can holdfrom about 500 to about 5000 gallons, for example, or even from about750 to about 2000 gallons (e.g., 1500 gallons). When the tank 220 isfilled with regenerant waste liquid 376 containing at least partially,the spent regenerant solution 100, the pump 124 is energized to transferthe liquid 376 to a regenerant recovery tank 296. The pump 124 can besimilar to the brine dosing pump described earlier but without the VFD.The water is pumped to the spent regenerant tank 220 until a high waterlevel float switch 208 in the tank activates after the tank 220 isfilled to the desired amount to de-energize the magnetic drive pump.

Jar tests of solution samples taken from the batch of regenerant wasteliquid 376 containing at least partially, the spent regenerant solution100, to be processed for recovery, are used to determine the appropriatechemicals and dosage of a regenerant treatment composition 111 needed totreat the regenerant waste liquid 376 (or spent regenerant solution 100,as used interchangeably herein) to remove undesirable chemicals, such asdivalent ions, while leaving behind desirable ions, such as sodium ions.A jar test can be performed for each new batch of spent regenerantsolution 100 to (1) establish the percent removal of divalent ions suchas strontium, barium, calcium, magnesium, and the total hardness forincreasing concentrations of calcium hydroxide and sodium carbonate, and(2) determine the regenerant treatment composition 111 in terms of dosesof hydrated lime or calcium hydroxide, sodium carbonate, and optionally,sodium hydroxide and/or hydrochloric acid which is required to recoverthe spent regenerant solution 100 in the form of a recovered regenerantsolution 186 comprising brine for subsequent resin regenerationprocesses.

Stock chemical solutions were prepared to facilitate the jar tests, andthese included:

(1) a calcium hydroxide solution comprising hydrated or slaked lime, ina concentration of 45 wt %, in water; and a

(2) a sodium carbonate solution comprising sodium carbonate (assumed 100percent pure) in a concentration of 100 mg/mL water with 50 gram in 500mL of distilled water;

(3) a sodium hydroxide solution comprising sodium hydroxide in aconcentration of 50 wt %, in water;

(4) a hydrochloric acid solution comprising a 100 mg/mL stock solutionformed by adding 116.6 mL of 37 percent hydrochloric acid (density=9.7lbs/gallon) into 500 mL of distilled water under a well ventilatedchemical hood with appropriate personal protection (e.g. safety glasses,compatible apron and gloves). The hydrochloric acid stock solution isused and stored per MSDS requirements.

To obtain sample spent regenerant solution 100 for the jar tests, a 1-or 2-gallon jar pre-rinsed with distilled water is filled with the spentregenerant solution 100 by opening the sample tap on the discharge ofthe magnetic drive pump during the spent regenerant transfer process.The gallon jar is filled at the same rate as that at which the reactionvessel is being filled to achieve a representative sample. The gallonjar sample is used to fill a smaller 500-mL graduated cylinder withspent regenerant solution 100. A salometer is floated in the cylinder toverify the salt concentration level in weight percent, after which the500 mL solution is poured back into the gallon container. The measuredsalt strength in the sample spent regenerant solution 100 should be readand is desirably at the strength level needed for regenerating spentresin 60. For example, the spent regenerant solution 100 should have asodium chloride concentration of from about 10 wt % to about 13 wt % toregenerate spent resin 60. If the solution strength is weaker than thedesired level, the backwash purge water, pre-brine water, last one-thirdof rinse water, and floor drain water should not be combined in the sump122 otherwise this would cause further dilution of the salinity andhardness of the spent regenerant solution 100 prior to treatment of thesame. If the solution strength is at or greater than the desired level,the quality of the spent regenerant solution 100 indicates that only thebrine is being sent to the reaction vessel.

At this stage, the batch of solution regenerant may need a laboratorytest or not, depending upon if a similar spent regenerant total hardnessconcentration was effectively treated and recorded in the past. If a labtest is desired, a set of appropriate sampling bottles are filled withsamples of the spent regenerant solution 100 from the gallon container.Jar tests are then conducted on these samples in a field laboratory todetermine total mineral hardness and solution composition. For example,a spent regenerant solution sample can be diluted in a ratio of 1:100(spent regenerant solution to water) with distilled water so thatcolorimetric total hardness and TDS field test kits can read thecomposition of the sample. A suitable colorimeter is a multi-parameterfield colorimeter capable of determining total hardness as CaCO₃, pH andtotal dissolved solids, such as, for example, an Orobeco Hellige MC500multi-parameter Field Colorimeter. A 10 mL sample of this solution issucked out with a pipette and transferred to an Erlenmeyer flask whereit is diluted with 990 mL of distiller water. A total hardness and TDStests are then performed on the water sample, and the results of thesetests are multiplied by 100 to get the actual concentration of salts inthe solution. The measured total hardness can be used to calculate theregenerant treatment composition 111 that needs to be added to the spentregenerant solution 100 to regenerate the solution.

In one version, the measured total hardness and other measured valuesfrom the spent regenerant solutions 100 are recorded in a tabularExcel™, Microsoft Corp spreadsheet having formulas therein—an exemplaryprintout being shown in Table I—to calculate the desired regeneranttreatment composition to reduce the total hardness level as CaCO₃ in thespent regenerant solution 100 to below 300 mg/L. The formulas used inTable I are as follows:

BS %=Brine Strength (% by weight) (where Brine refers to a regenerantsolution comprising sodium chloride dissolved in water.BS#=Brine Strength (lb salt/gal water)

BS#=0.0007×BS %²+0.0824×BS %+0.0019

BS_(DEGREE)=Brine Strength (degree salometer)

BS _(DEGREE)=3.7887×BS %−0.0024

V_(RESIN)=Volume of resin per batch (cf)D_(SALT)=Salt Dosage (lb salt/cf of resin)=Determined from desiredcapacity from MFR curvesW_(SALT)=Weight of Salt per regeneration batch (lb salt/regen)

W _(SALT) =D _(SALT) ×V _(RESIN)

V_(REGEN)=Volume of Brine per Regeneration batch (gal brine/regen)

$V_{REGEN} = \frac{W_{SALT}}{{BS}\#}$

HRT_(BRINE)=Hydraulic Retention Time for Brining (min)=specified byMFR=0.5 gpm/cf=15 minQ_(BRINE)=Brine Flow Rate (gpm)=MFR suggested flow rate to achievedesired contact time

$Q_{BRINE} = \frac{V_{REGEN}}{H\; R\; T_{BRINE}}$

T_(BRINE)=Duration of Brining (min)

$T_{BRINE} = \frac{V_{REGEN}}{Q_{BRINE}}$

D_(VESSEL)=ID of Reaction Vessel (in)

H_(SS)=Side shell Height of Reaction Vessel (in)=HWL pump cutoffWL=Water Level=Water level in reaction vessel at end of treatment cycle

$V_{SEED} = {\pi \frac{\left( {D_{VESSEL}/12} \right)^{2}}{4} \times \left( \frac{W\; L}{12} \right) \times 7.48}$

V_(BATCH)=Treated Volume (gal)=Reaction vessel batch volume used inchemical dose calculations.V_(TOTAL)=Total Volume (gal)=Reaction vessel total volume

$V_{TOTAL} = {\pi \frac{\left( {D_{VESSEL}/12} \right)^{2}}{4} \times \left( \frac{H_{SS}}{12} \right) \times 7.48}$V _(BATCH) =V _(TOTAL) −V _(SEED)

V_(SAMPLE)=Sample Volume of Jar Test (mL)=Volume of spent brine thatwill have chemistry added to it=500 mLW_(LIME)=Weight of Calcium Hydroxide (Lime) Added to V_(SAMPLE)(g)=Amount of chemical that gave favorable total hardness removalresults after mixing, settling and lab centrifugeW_(NAOH)=Weight of Sodium Hydroxide Added to V_(SAMPLE) (g)=Amount ofchemical that gave favorable total hardness removal results aftermixing, settling and lab centrifugeW_(SODA)=Weight of Sodium Carbonate (Soda Ash) Added to V_(SAMPLE)(g)=Amount of chemical that gave favorable total hardness removalresults after mixing, settling and lab centrifugeD_(LIME)=Calcium Hydroxide (Lime) Dosage (g/mL)

$D_{LIME} = \frac{W_{LIME}}{V_{SAMPLE}}$

D_(NAOH)=Sodium Hydroxide Dosage (g/mL)

$D_{NAOH} = \frac{W_{NAOH}}{V_{SAMPLE}}$

D_(SODA)=Sodium Carbonate (Soda Ash or Soda) Dosage (g/mL)

$D_{SODA} = \frac{W_{SODA}}{V_{SAMPLE}}$

D_(LIME,batch)=Calcium Hydroxide (Lime) Dosage of Treatment Batch(lb/gal)

$D_{{LIME},{batch}} = {\frac{D_{LIME}}{453.6} \times 3785}$

W_(LIME,batch)=Weight of Bagged Lime to Add to Batch (lbs)

W _(LIME,batch) =D _(LIME,batch) ×V _(BATCH)

D_(NAOH,batch)=Sodium Hydroxide Dosage of Treatment Batch (lb/gal)

$D_{{NAOH},{batch}} = {\frac{D_{NAOH}}{453.6} \times 3785}$

W_(NAOH,batch)=Weight of Bagged Sodium Hydroxide to Add to Batch (lbs)

W _(NAOH,batch) =D _(NAOH,batch) ×V _(BATCH)

D_(SODA,batch)=Soda Ash Dosage of Treatment Batch (lb/gal)

$D_{{SODA},{batch}} = {\frac{D_{SODA}}{453.6} \times 3785}$

W_(SODA,batch)=Weight of Bagged Soda Ash to Add to Batch (lbs)

W _(SODA,batch) =D _(SODA,batch) ×V _(BATCH)

D_(RV)=ID of Reaction Vessel (ft)=5.79 ftA_(RV)=Cross Sectional Area of Reaction Vessel (ft²)

$A_{RV} = {\pi \frac{D_{RV}^{2}}{4}}$

A_(RV)=Cross Sectional Area of Reaction Vessel (ft²)LVL_(RV)=Drop of HCL Level in Reaction Vessel (in)=Required to depresspH to near neutralV_(INCR)=Incremental Volume of Reaction Vessel (gal/in)

$V_{INCR} = {A_{RV} \times \frac{7.48}{12}}$

C_(HCL,batch)=Hydrochloric Acid Consumption at 31% Concentration(gal/batch)=Amount of HCL needed to bring the treated regenerantsolution pH back to near neutral

C _(HCL,batch) =V _(INCR) ×LVL _(RV)

$_(HCL,unit)=31% HCL Unit Cost ($/gal)=1.53 $/gal$_(HCL,batch)=31% HCL Cost per batch ($/batch)

$_(HCL,batch) =C _(HCL,batch)×$_(HCL,batch)

$_(LIME,unit)=99% Lime Unit Cost ($/lb)=0.17 $/lb$_(LIME,batch)=99% Lime Cost per batch ($/batch)

$_(LIME,batch) =W _(LIME,batch)×$_(LIME,unit)

$_(NAOH,unit)=99% Sodium Hydroxide Unit Cost ($/lb)=0.33 $/lb$_(NAOH,batch)=99% Sodium Hydroxide Cost per batch ($/batch)

$_(NAOH,batch) =W _(NAOH,batch)×$_(NAOH,unit)

$_(SODA,unit)=99% Soda Ash Unit Cost ($/lb)=0.25 $/lb$_(SODA,batch)=99% Soda Ash Cost per batch ($/batch)

$_(SODA,batch) =W _(SODA,batch)×$_(SODA,unit)

ZLD Chemical Dose Calcs Table Legend Columns with a * indicate acalculation. Columns without a * indicate an assumption or data entryfield. Chemical Costs: HCL = 1.52 $/gal Lime = 0.17 $/lb NaOH = 0.33$/lb Soda Ash = 0.25 $/lb Columns in the table, listed from left toright, are: Salometer: Neat brine salt concentration used to regeneratethis batch that was just treated. Dosage: Salt dosage used to regeneratethis batch that was just treated. Dilution Ratio: The dilution rationeeded for the colorimeter, but only multiply TEST 201 total hardnessresult by 100 Total Hardness: The total hardness of the spent brine tobe treated TDS: Total dissolved solids of the raw water spent brinetaken in 1:1000 diluted sample pH (pre-dilution): Actual pH of spentbrine b4 dilution occurs pH (Colorimeter): PH of 1:1000 Diluted THsample in colorimeter . . . must be between 6.5 and 7.5 Salometer: Spentbrine salt concentration used to regenerate this batch that was justtreated. Level: Level of treated brine left over in the bottom of 1,000gal white tank SEED Volume*: Calculated volume of treated water leftover in white 1,000 gal tank BATCH Volume*: Calculated volume of actualtreated water that equals the total volume in white tank minus the seedvolume Lime: Weight of calcium hydroxide (Ca(OH)2), or lime, per batchvolume required to remove the temporary hardness in the spent brineSodium Hydroxide: Weight of sodium hydroxide (NaOH) per batch volumerequired to remove the temporary hardness in the spent brine Soda Ash:Weight of sodium carbonate (Na2CO3), or soda ash, required to remove thepermanent hardness and any excess Ca in the spent Total Hardness inWhite Tank: The total hardness of the chemically treated spent brinetaken in the white tank after settling for 10 minutes. This sample mustbe placed in the lab centrifuge b4 analyzing in the colorimeter TotalHardness at PUMP: The total hardness of the chemically treated, filterpressed and pH adjusted brine taken at the discharge of the transferpump Total Hardness POST FILTER: The total hardness of the chemicallytrated, filter pressed and pH adjusted brine taken after the cartridgefilter in case any solids passed through the press. pH-high: The highestpH the filtrate reached in the balck tank taken while the mixer is on,after all of the pH-low: The lowest pH the filtrate reached in the blacktank while the mixer is on after adding the HCL pH (Colorimeter): pH ofthe 1:10 diluted treated brine total hardness sample HCL Consumption*:The volume calculation from the level drop in the HCL tank PressCleaned?: Note if the filter press has been cleaned. Time to Treat: Thetotal time it took to press the chemically treated spent brineSalometer: Chemically treated neat brine salt concentration ChemicalCost*: Only the chemical cost to treat the batch volume, based onChemical Costs above

TABLE I Dosage Calculations RW FIELD TESTS BATCH BRINE Total SEED SodiumSalometer Dosage Dilution Hardness TDS pH pH Salometer Level VolumeVolume Lime Hydroxide (%) (#cf) Ratio (ppm) (ppm) (pre-dilution)(Colorimeter) (%) (in) (gal) (gal) (lb) (lb) 10.0 15 1:1000 13,000 64,000 — — 9 5.0 82 887 50 50 10.0 15 1:1000 14,000 — — — 9 4.5 74 89550 50 10.0 15 1:1000 13,500  80,000 — — 7.8 4.5 74 895 50 50 12.0 151:1000 13,500 — — — — 4.5 74 895 50 50 12.0 15 1:1000 15,000 — — — — 5.082 887 50 50 12.0 15 1:1000 16,000 — — — 8.5 5.0 82 887 50 50 12.0 151:1000 17,000  80,600 — — 8.5 3.5 57 1,035 50 50 12.0 15 1:1000 17,000 80,600 — — 8.5 3.5 57 1,035 50 50 13.0 15 1:1000 18,000 — — — 9.0 4.066 1,026 50 50 13.0 15 1:1000 12,000 — — — 9.0 4.0 66 1,026 50 50 — —1:1000 17,000 — — — 10.5 4.5 74 1,018 50 50 — 15 1:1000 15,000 — — —10.0 4.5 74 1,018 50 50 13.0 15 1:1000 18,100 — — — 10.0 4.0 66 1,026 5050 13.0 15 1:1000 18,000 — — — 9.5 4.5 74 1,018 50 50 13.0 15 1:100015,000 — — — 9.5 4.5 74 1,018 50 50 13.0 15 1:1000 21,700 154,000 — —9.0 4.5 74 1,018 50 50 13.0 15 1:1000 28,000 — — — 12.0 4.5 74 1,018 5050 14.0 15 1:1000 29,400 188,400 — — 12.0 4.5 74 1,018 50 50 12.0 151:1000 22,400 189,100 — — 11.5 5.0 82 1,010 50 50 14.5 15 1:1000 27,600190,800 — — 11.5 5.0 82 1,010 50 50 12.0 15 1:1000 27,500 >200k — — 11.55.0 74 1,018 50 50 12.0 15 1:1000 21,800 >200k — — 11.0 5.0 82 1,010 2525 12.0 15 1:1000 26,500 186,200 — — 11.0 4.5 82 1,010 25 25 11.0 151:1000 19,900 188,400 — — 11.0 5.0 82 1,026 50 50 11.0 15 1:1000 26,000191,100 — — 11.0 4.0 66 1,018 50 50 11.0 15 1:1000 17,000 — — — 11.0 4.574 1,018 50 50 11.0 15 1:1000 17,000 — — — 11.0 4.5 74 1,018 50 50 11.015 1:1000 17,000 — — — 11.0 4.5 74 1,018 50 50 11.0 15 1:1000 15,000 — —— 11.0 4.5 74 1,018 50 50 11.0 15 1:1000 23,600 190,600 — — 11.0 4.0 661,026 50 50 12.0 15 1:1000 29,500 180,900 6.00 — 11.0 4.0 66 1,026 50 5012.0 15 1:1000 15,700 192,200 6.06 — 11.0 5.0 82 1,010 50 50 12.0 151:1000 28,600 — — — 11.0 5.0 82 1,010 50 50 12.0 15 1:1000 39,300 >200k6.84 — 11.0 4.0 66 1,026 75 75 12.0 15 1:1000 31,700 >200k 6.10 — 11.05.0 82 1,010 50 50 12.0 15 1:1000 31,100 >200k 5.98 — 11.0 4.5 74 1,01850 50 12.0 15 1:1000 27,200 >200k 6.70 — 11.0 4.5 74 1,018 50 50 12.5 151:1000 31,100 >200k 6.70 6.70 11.0 4.0 66 1,026 50 50 10.0 15 1:100030,000 195,200 6.70 6.60 11.0 4.5 74 1,018 50 50 12.0 15 1:1000 33,200 —6.80 — 11.0 4.5 74 1,018 50 50 12.0 15 1:1000 27,900 — 6.75 — 10.5 4.574 1,018 50 50 12.0 15 1:1000 25,300 — 6.75 — 10.0 4.5 74 1,018 50 5010.0 15 1:1000 26,700 — 6.61 — 10.0 4.5 74 1,018 50 50 10.0 15 1:100027,600 — 6.75 — 10.0 4.5 74 1,018 50 50 13.0 15 1:1000 35,300 175,1006.70 7.13 11.0 4.0 66 1,026 50 50 13.0 15 1:1000 27,000 >200k 6.79 7.2711.5 4.5 74 1,018 50 50 BATCH Total Total Hardness BRINE Hardness POSTHCL Press COST Salometer Dosage Soda @ PUMP FILTER pH- pH- ConsumptionHCL Salometerr cleaned? Chemical (%) (#cf) Ash (ppm) (ppm) high low (in)Consumption (%) (Y/N) ($/kgal) * 10.0 15 150 10 — — — — — 9 N 70.48 10.015 175 10 — — — — — 9 N 76.82 10.0 15 175 10 — — — — — 9 N 76.82 12.0 15175 10 — 12.9 7 — — 8.5 N 76.82 12.0 15 175 10 — 12.9 6.5 — — 8.5 N77.53 12.0 15 200 20 — 12 7.5 — — 9 Y 84.58 12.0 15 225 20 — 12.8 7.8 —30 9 N 122.90 12.0 15 200 2 — — — — — — — 72.49 13.0 15 225 2 — 12.9 7 —30 10 N 123.89 13.0 15 175 2 — 12.8 6.7 — 30 9.5 N 111.71 — — 225 2 — —— — — — — 79.80 — 15 200 2 — 12.5 7 — 30 — Y 18.75 13.0 15 225 2 — 12.86.5 — 30 12.5 N 123.89 13.0 15 225 8 — 12.7 7.4 — 30 10 N 124.88 13.0 15200 2 — 12.1 7.5 — 30 10 N 118.75 13.0 15 225 50 — 12.3 7.3 — 30 10 Y124.88 13.0 15 250 10 — 12.4 7.4 — 30 10 N 131.02 14.0 15 250 12 — 12.67.1 — 30 10 N 131.02 12.0 15 200 23 — 121.7 6.9 — 25 12 N 112.14 14.5 15225 16 — 11.8 6.9 — 25 12 Y 118.32 12.0 15 200 8 — 11.8 8.1 — 20 12 N103.72 12.0 15 150 19 — 11.4 3.2 —  5 11.5 N 57.08 12.0 15 200 330 —11.6 7.3 —  5 11.5 N 69.46 11.0 15 150 >600 — 12 3.6 — 10 11 Y 77.0311.0 15 200 60 — 12.6 6 — 30 11 N 73.07 11.0 15 225 40 — 12 6.2 — 30 11Y 109.86 11.0 15 225 40 — 11.8 6.5 — 25 11 N 109.86 11.0 15 225 140 —11.9 8.3 — 25 11 N 109.86 11.0 15 200 300 — 11.6 7.2 — 20 11.5 N 103.7211.0 15 200 17 — 12.6 2.6 —  5 12 N 87.98 12.0 15 250 11 — 12.4 6.7 —  512 Y 100.16 12.0 15 200 9 — 12.4 6.7 — 10 11 N 89.41 12.0 15 250 336 —12 6.9 — — 12 N 86.64 12.0 15 300 6 26 12.6 7.6 — 20 12 N 139.43 12.0 15225 25 43 12.6 7.2 — 10 11 N 95.60 12.0 15 225 173 — 11.2 5.6 — 10 11.5Y 94.83 12.0 15 225 5 28 11.7 6.4 — 10 11.5 N 94.83 12.5 15 235 22 2711.8 6.2 — 10 11 N 96.51 10.0 15 215 256 263  11.8 5.8 — 10 11 N 92.3712.0 15 250 175 240  11.8 7 — 10 11 Y 100.97 12.0 15 225 266 over 11.77.2 — 10 11 N 94.83 12.0 15 200 490 over 11.9 7.5 — 15 11 N 96.20 10.015 225 338 383  11.7 7 — 15 11 N 102.34 10.0 15 225 214 306  11.7 7 — 1511 Y 102.34 13.0 15 250 31 35 12 6.6 2 16 11.5 N 109.10 13.0 15 225 248— 11.9 6.4 2.375 19 — N 108.35

For example, in one version, the appropriate calcium hydroxide, sodiumhydroxide and sodium carbonate dosage per 500 mL sample from thespreadsheet shown in Table I, will bring the total hardnessconcentration in the regenerant waste liquid 376 or spent regenerantsolution 100 down to <80 mg/L is determined from the dosage spreadsheetand then the calculated result verified with additional jar tests. Aplurality of different dosage concentrations can be determined, forexample, at least three or even at least four different compositions ofregenerant solution 186. In one version, the calcium hydroxide andsodium hydroxide doses are approximately equal to each other, and thesodium carbonate dose is from about 3 to about 10 times the total amountof calcium hydroxide and sodium hydroxide. Either calcium hydroxide orsodium hydroxide, or both, can be used.

When four dosage levels are selected, four 500-mL graduated cylindersare filled with spent regenerant solution 100 out of the galloncontainer sample, and each regenerant treatment composition 111 is addedto one of the graduated cylinders. With the top of graduated cylindercovered (for example, with an operator's hand with rubber glove on),each of the four graduated cylinder samples is aggressively shaken for 1minute to mix the chemicals and liquid in the cylinder. Two of the foursamples from the 500-mL graduated cylinders are then taken, and fromthese, 3×15 mL=45 mL of each sample poured into three 15-mL test tubesfor centrifuging. The rubber stoppers on the test tubes should be markedwith the sample number so that it can be identified. Two sets of samplesof 3 each can be spun at the same time in a laboratory centrifuge having6 slots. The centrifuge is turned on for 1 minute to separate thetreated regenerant liquid 342 into precipitated solids and supernatant.The clear supernatant liquid in each sample test tube is poured into a50-mL beaker and a pH meter inserted in the beaker to record a reading.Thereafter, a jar test is performed with a pH adjuster 351, such as theacid 231, for example, diluted hydrochloric acid (e.g., in a 31%strength) to determine the volume needed to depress the treatedregenerant liquid 342 to be within a neutral pH range. The dilutedhydrochloric acid is added to these beakers and the pH measured untilthe pH is near neutral. Any of the regenerant treatment composition 111samples that reduced the hardness of the spent regenerant solution 100to less than 300-mg/L, as measured from the field colorimeter andcolumns of Table I, is selected for use as the regenerant treatmentcomposition 111 for the current batch of regenerant solution 186. Thetotal hardness concentration of the treated samples in the graduatedcylinders as determined from the pH adjusting tests is read using theEndress+Hauser pH probe. In this example, a regeneration treatmentcomposition 111, comprising at least one hydroxide compound and at leastone carbonate compound, is used to remove ions from the spent regenerantsolution 100 in the form of precipitate flocs 114 of precipitatedhydroxide and carbonate compounds. For example, the regenerationtreatment composition 111 can remove divalent ions such as magnesium orcalcium, barium, and other ions from the solution 100, as can be notedin the previous table.

The hydroxide compounds are provided to precipitate metal ion hydroxidesthat are insoluble, such as magnesium hydroxide. Suitable hydroxidecompounds include, for example, calcium hydroxide, sodium hydroxide, andalkali or alkaline earth metal hydroxides. The hydroxide compound canalso include a mixture of calcium hydroxide and sodium hydroxide.Advantageously, a mixture of calcium hydroxide and sodium hydroxide notonly precipitates compounds from the spent regenerant solution 100 butalso serves to add sodium ions to replenish the sodium ion concentrationwithin the spent regenerant solution 100. The addition of sodiumhydroxide assists in decreasing the sludge volume by producing a densersludge. In this example, the calcium hydroxide is obtained from ahydroxide source such as a calcium hydroxide source 312 a, and thesodium hydroxide is obtained from a hydroxide source such as a sodiumhydroxide source 312 b, as shown in FIG. 5B.

In one version, the regenerant treatment composition 111 comprises ahydroxide component comprising a mixture of calcium hydroxide and sodiumhydroxide, and a carbonate compound comprising sodium carbonate.Advantageously, a mixture of calcium hydroxide and sodium hydroxide notonly precipitates compounds from the spent regenerant solution 100, butalso serves to add sodium ions to replenish the sodium ion concentrationwithin the spent regenerant solution 100. The addition of sodiumhydroxide assists in decreasing the sludge volume by producing a densersludge. The amount of the regenerant treatment composition 111 added tothe spent regenerant solution 100 to remove all the mineral hardness isdetermined by the background or baseline total mineral hardness in mg/Las CaCO₃. The mineral hardness concentrations in spent regenerantsolution 100 used to regenerate a 120 cubic foot batch of spent resin 60can be from about 10,000 to about 50,000 mg/L as CaCO₃ depending on howexhausted the spent resin 60 is at the time of the regeneration.

In one example, useful for treating spent regenerant solution 100derived from sodium chloride regenerated resin 194, a regeneranttreatment composition 111 comprising calcium hydroxide, sodium hydroxideand sodium carbonate, is added to the spent regenerant solution 100 toprecipitate compounds to achieve a total mineral hardness in the treatedand separated regenerant solution 374 of less than 300 mg/L in the formof CaCO₃. In one example, to achieve a total hardness concentration inthe spent regenerant solution of less than 10,000 mg/L as CaCO₃, or lessthan 0.09991 moles/L as CaCO₃, can require from about 0.005 to about 38moles/L of calcium hydroxide, or even from about 0.006 moles/L to about0.06 moles/L calcium hydroxide, or more specifically 0.03 moles/Lcalcium hydroxide; from about 0.007 to about 53 moles/L sodiumhydroxide, or even from about 0.015 moles/L to about 0.14 moles/L sodiumhydroxide, or more specifically 0.075 moles/L sodium hydroxide; fromabout 0.002 to about 24 moles/L sodium carbonate, or even from about0.034 moles/L to about 0.3 moles/L sodium hydroxide, or morespecifically 0.17 moles/L sodium carbonate.

As another example, to achieve a total hardness concentration in thespent regenerant solution of from about 10,000 to about 25,000 mg/L asCaCO₃, or from 0.1 to about 0.25 moles/L as CaCO₃, can require fromabout 0.005 to about 38 moles/L of calcium hydroxide, or even about 0.01moles/L to about 0.09 moles/L calcium hydroxide, or more specifically0.05 moles/L calcium hydroxide; from about 0.007 to about 53 moles/Lsodium hydroxide, or even from about 0.015 moles/L to about 0.14 moles/Lsodium hydroxide, or more specifically 0.075 moles/L sodium hydroxide;from about 0.002 to about 24 moles/L sodium carbonate, or even about0.045 moles/L to about 0.4 moles/L sodium carbonate, or morespecifically 0.23 moles/L sodium carbonate.

As still another example, to achieve a total hardness concentration inthe spent regenerant solution of from about 25,000 to about 35,000 mg/Las CaCO₃, or 0.25 to about 0.35 moles/L as CaCO₃, can require from about0.005 to about 38 moles/L of calcium hydroxide, or even about 0.01moles/L to about 0.09 moles/L calcium hydroxide, or more specifically0.05 moles/L calcium hydroxide; from about 0.007 to about 53 moles/Lsodium hydroxide, or even about 0.015 moles/L to about 0.14 moles/Lsodium hydroxide, or more specifically 0.075 moles/L sodium hydroxide;from about 0.002 to about 24 moles/L sodium carbonate, or even about0.057 moles/L to about 0.5 moles/L sodium carbonate, or morespecifically 0.28 moles/L sodium carbonate.

As yet another example, to achieve a total hardness concentration in thespent regenerant solution of from about 35,000 to about 45,000 mg/L asCaCO₃, or 0.35 to about 0.45 moles/L as CaCO₃, can require from about0.005 to about 38 moles/L of calcium hydroxide, or even about 0.01moles/L to about 0.09 moles/L calcium hydroxide, or more specifically0.05 moles/L calcium hydroxide; from about 0.007 to about 53 moles/Lsodium hydroxide, or even about 0.015 moles/L to about 0.135 moles/Lsodium hydroxide, or more specifically 0.075 moles/L sodium hydroxide;from about 0.002 to about 24 moles/L sodium carbonate, or even about0.07 moles/L to about 0.6 moles/L sodium carbonate, or more specifically0.34 moles/L sodium carbonate.

As another example, to achieve a total hardness concentration in thespent regenerant solution of greater than 45,000 mg/L as CaCO₃, or 0.45moles/L as CaCO₃, can require from about 0.005 to about 38.05 moles/L ofcalcium hydroxide, or even about 0.01 moles/L to about 0.09 moles/Lcalcium hydroxide, or more specifically 0.05 moles/L calcium hydroxide;from about 0.007 to about 53 moles/L sodium hydroxide, or even about0.02 moles/L to about 0.2 moles/L sodium hydroxide, or more specifically0.1 moles/L sodium hydroxide; from about 0.002 to about 24 moles/Lsodium carbonate, or even about 0.08 moles/L to about 0.7 moles/L sodiumcarbonate, or more specifically 0.4 moles/L sodium carbonate.

The above defined ratios can provide the benefit of consistent removalof the total hardness to less than 300 mg/L as CaCO₃ while stillmaintaining the salinity, or salt concentration of from about 10% toabout 13% by weight, required to regenerate subsequent spent cationicresin.

In another example, useful for spent regenerant solution derived frompotassium chloride regenerated resin, a regenerant treatment compositioncomprising calcium hydroxide, potassium hydroxide and potassiumcarbonate, is added to the spent regenerant solution to precipitatecompounds to achieve a total mineral hardness in the treated andseparated regenerant solution of less than 300 mg/L in the form ofCaCO₃. Assuming that the regenerant treatment composition comprises 99%pure calcium hydroxide, potassium hydroxide and potassium carbonate, thefollowing dosages can result in treated regenerant liquid containingtotal hardness levels less than 300 mg/L as CaCO₃.

As an example, to achieve a total hardness concentration in the spentregenerant solution of less than 10,000 mg/L as CaCO₃ or less than0.09991 moles/L as CaCO₃, can require from about 0.005 to about 38moles/L of calcium hydroxide, or even about 0.006 moles/L to about 0.055moles/L calcium hydroxide, or more specifically 0.03 moles/L calciumhydroxide; from about 0.007 to about 36 moles/L potassium hydroxide, oreven about 0.015 moles/L to about 0.13 moles/L potassium hydroxide, ormore specifically 0.075 moles/L potassium hydroxide; from about 0.002 toabout 16.6 moles/L potassium carbonate, or even about 0.034 moles/L toabout 0.3 moles/L potassium carbonate, or more specifically 0.17 moles/Lpotassium carbonate.

As another example, to achieve a total hardness concentration in thespent regenerant solution of from about 10,000 to about 25,000 mg/L asCaCO₃, or 0.1 to about 0.25 moles/L as CaCO₃, can require from about0.005 to about 38 moles/L of calcium hydroxide, or even about 0.01moles/L to about 0.09 moles/L calcium hydroxide, or more specifically0.05 moles/L calcium hydroxide; from about 0.007 to about 36 moles/Lpotassium hydroxide, or even about 0.015 moles/L to about 0.135 moles/Lpotassium hydroxide, or more specifically 0.075 moles/L potassiumhydroxide; from about 0.002 to about 16.6 moles/L potassium carbonate,or even about 0.045 moles/L to about 0.4 moles/L potassium carbonate, ormore specifically 0.23 moles/L potassium carbonate.

As still another example, to achieve a total hardness concentration inthe spent regenerant solution of from about 25,000 to abut 35,000 mg/Las CaCO₃, or from about 0.25 to about 0.34 moles/L as CaCO₃, can requirefrom about 0.005 to about 38 moles/L of calcium hydroxide, or even about0.01 moles/L to about 0.09 moles/L calcium hydroxide, or morespecifically 0.052 moles/L calcium hydroxide; from about 0.007 to about36 moles/L potassium hydroxide, or even about 0.015 moles/L to about0.14 moles/L potassium hydroxide, or more specifically 0.075 moles/Lpotassium hydroxide; from about 0.002 to about 16.6 moles/L potassiumcarbonate, or even about 0.057 moles/L to about 0.5 moles/L potassiumcarbonate, or more specifically 0.28 moles/L potassium carbonate.

As yet another example, to achieve a total hardness concentration in thespent regenerant solution of from about 35,000 to about 45,000 mg/L asCaCO₃, or from about 0.35 to 0.45 moles/L as CaCO₃, can require fromabout 0.005 to about 38 moles/L of calcium hydroxide, or even about 0.01moles/L to about 0.09 moles/L calcium hydroxide, or more specifically0.052 moles/L calcium hydroxide; from about 0.007 to about 36 moles/Lpotassium hydroxide, or even about 0.015 moles/L to about 0.14 moles/Lpotassium hydroxide, or more specifically 0.075 moles/L potassiumhydroxide; from about 0.002 to about 16.6 moles/L potassium carbonate,or even about 0.069 moles/L to about 0.61 moles/L potassium carbonate,or more specifically 0.34 moles/L potassium carbonate.

As a further example, to achieve a total hardness concentration in thespent regenerant solution 100 of greater than about 45,000 mg/L asCaCO₃, or 0.4496 moles/L as CaCO₃, can require from about 0.005 to about38 moles/L of calcium hydroxide, or even about 0.01 moles/L to about0.09 moles/L calcium hydroxide, or more specifically 0.05 moles/Lcalcium hydroxide; from about 0.007 to about 36 moles/L potassiumhydroxide, or even about 0.02 moles/L to about 0.2 moles/L potassiumhydroxide, or more specifically 0.1 moles/L potassium hydroxide; fromabout 0.002 to about 16.6 moles/L potassium carbonate, or even about0.09 moles/L to about 0.7 moles/L potassium carbonate, or morespecifically 0.4 moles/L potassium carbonate. These ratios provide thebenefits of consistent removal of the total hardness to less than 300mg/L as CaCO3 while still maintaining the salinity, or saltconcentration of from about 10% to about 13% by weight, required toregenerate subsequent spent cationic resin.

In any of the illustrative examples provided above, in addition to theregenerant treatment composition, a ph adjuster 351 can be added to thetreated regenerant liquid 342 to change the pH of the treated and/orseparated regenerant liquid to acceptable levels. The ph adjuster 351can be added during the treatment process, for example, while theregenerant treatment composition is being stirred into the regenerantwaste liquid 376 containing at least partially, the spent regenerantsolution 100, or afterwards, after separation of the precipitatedcompounds. In one example, the ph adjuster 351 comprises a chloride ioncompound, such as hydrochloric acid. As one example, ph adjuster 351comprising hydrochloric acid in a concentration of about 31.5% can beadded in an amount of from about 8 gallons to about 16 gallons for every1,000 gal of treated regenerant solution to bring the pH to anacceptable range of from about 4.5 to about 7.5, or more specificallyfrom about 5 to about 6 to re-dissolve the calcium carbonate precipitatethat may form in the vats during and after brining.

After the correct composition of a regenerant treatment composition 111suitable for the current batch of regenerant waste liquid 376 containingat least partially, the spent regenerant solution 100, is determinedusing the sample jar tests, a scaled-up dosage composition of theregenerant treatment composition 111 needed to treat the amount of spentregenerant solution 100 in the reaction vessel is calculated using aDosage spreadsheet. For example, when the amount of spent regenerantsolution 100 in the reaction vessel is about 1500 gallons, the scaled-updosage composition of the regenerant treatment composition 111 to treatthis volume of regenerant liquid is calculated as follows:

After the jar tests are done, a regenerant treatment composition 111comprising the desired concentrations of calcium hydroxide, sodiumhydroxide and sodium carbonate is then weighed out for mixing with theregenerant waste liquid 376 containing at least partially, the spentregenerant solution 100. In this step, the regenerant treatmentcomposition 111 is weighed out in a first chemical dispenser 280 thatincludes a mixing well 282 in which the chemicals are mixed before theirintroduction into the regenerant recovery tank 296. The mixing well 282has a conical shape with several wash-down nozzles 284 which spray andmist water down the internal sides of the mixing well 282 in a spiralmanner to reduce the airborne particulate matter and further dilute thechemicals, as shown in FIG. 3C. To mix in the chemicals, the diaphragmpump 65 is started, and the gauges are allowed to cycle completely backand forth by turning on the compressor powered by the diesel engine 600.The diaphragm pump 65 can be powered by an air compressor, which in turnis driven by a shaft connected to a diesel engine 600 to provide an airpowered pump having a high flow rate, high demand availability, andrapid duty cycle. The valves of the recovery system are configured sothat the diaphragm pump 65 energizes the closed flow pumps in a closedloop while the regenerant treatment composition 111 is added to theregenerant waste liquid 376. The diaphragm pump 65 is used to drawregenerant waste liquid 376 from the bottom of the regenerant recoverytank 296 as the motive flow for the chemical addition. The pump 65 canalso be a rotary screw air compressor, such as one rated up to 200 csmat 150 psi, and which does not generally need a reservoir. A peristalticpump 79 similar to the ones used for brining and resin transfer, canalso be used as an alternative method of pumping the chemically-dosed,regenerant waste liquid 376 without shearing the precipitate flocs 114formed therein.

A pulse dampener 560 is connected to the pump 65 to reduce any “waterhammer effect” to even out the flow of water from pump 65. In oneversion, a pulse dampener 560 may be connected to the pump 65 via aconnector 554. A suitable pulse dampener 560 may be, for example, aSentury pulsation dampener from BLACOH LIQUID CONTROL, Riverside Calif.Other accessories can also be implemented in the solids separator 500,such as a baffle, circulation pump, submersible suction device or thelike.

A supply of regenerant waste liquid 376 from the recovery tank outlet107 of the regenerant recovery tank 296 is pumped through the piping 334(with the valves 125 a-d in an open position and valve 125 e in a closedposition) using a diaphragm pump 65, so that a stream of regenerantwaste liquid 376 mixes with the chemicals from the chemical dispenser280 to form a solution stream comprising treated regenerant liquid 342comprising the regenerant treatment composition 111 which is then fedinto the second inlet 109 b at the top of the regenerant recovery tank296 to complete a closed loop system that is open to the atmosphere.

During mixing of the chemicals via the chemical dispenser 280 into theregenerant waste liquid 376 to form the treated regenerant liquid 342,the chemically-dosed treated regenerant liquid 342 is returned to theregenerant recovery tank 296 by the diaphragm pump 65 which continues topump the water in a loop until all of the regenerant treatmentcomposition 111 has been added. The treated regenerant liquid 342 issent back to regenerant recovery tank 296 for slower mixing with theimpeller mixer 322. The impeller mixer 322 in the regenerant recoverytank 296 is energized when the initial chemical addition begins, and itcan stop after all of the chemistry is added to the fixed volume oftreated regenerant liquid 342. The slower mixing achieves a mixingintensity of from about 10 to about 15 s⁻¹ allowing flocs 114 ofprecipitated compounds to form in the chemically-treated solution.

After mixing in all the chemicals and when the hardness level isdetermined to be acceptable, the treated regenerant liquid 342 is passedthrough a solids separator 500 to separate out the precipitate flocs 114formed in the liquid 342. In one version, the solids separator 500comprises a filtering system 324, such as a filter press 300. In thisprocess, the diaphragm pump 65 is started, the impeller mixer 322 isturned off, and the various valves 125 a-e configured reconfigured topass the treated regenerant liquid 342 to the filter press 300 of thesolids separator 500. For example, opening valves 125 a, 125 c, and 125e direct the liquid 342 containing the precipitates 114 into and throughthe filter press 300. A suitable filter press 300 provides filtrationand separation of particles sized from 0.1 to about 100 microns, such asfrom 1 to 20 microns (e.g., 5 micron). During the filter pressingoperation, the impeller mixer 322 in the regenerant recovery tanks 296is turned off. The residue from the filter press 300 comprises solidsgenerated in the form of the filter cakes comprises precipitatedcompounds, including precipitated calcium carbonate and magnesiumhydroxide. The filter cakes are transferred and stored in the solidsdisposal dump 346, and they can be resold or disposed of as determinedfrom Toxicity Characteristic Leaching Potential Tests, WET, LandfillLeachate Tests and Aqueous Solubility Tests Leaching, conducted by TheUniversity of Arizona.

The supernatant or filtrate liquid from the filter press 300 enters thetop of the regenerant recovery tank 296 in a closed loop through adedicated recirculation line where it is visually inspected, and oncethe filtrate clarifies to drinking water clarity, the valves 125 a-e arereset to allow all of the filtered liquid flow to enter the pH-adjustingtank 350. As an alternative to looking into the regenerant recovery tank296 to see if the filtrate is of acceptable clarity to then transfer tothe pH-adjusting tank 350, a short segment of clear PVC pipe can be usedupstream or downstream of the diversion valves that redirect the clearfiltrate from the regenerant recovery tank 296 to the pH-adjusting tank350.

The treated regenerant liquid 342 is pumped through the filter press 300across valve 125 e and into a regenerant pH-adjusting tank 350. The pHof the treated and filtered regenerant liquid 342 is adjusted in thetank 350 by adding a pH adjuster 351 to set the pH to the desired leveland also to have a sufficient number of chloride ions to balance thesodium ions which were increased by adding the sodium hydroxide in theregenerant treatment composition 111. The chloride ions added using achloride ion source 386 which can be hydrochloric acid, held in thepH-adjuster tank 387, which is pumped using a pH-adjuster feed pump 389to an inlet 392 of the tank 350. A second impeller mixer 394 is used tomix the hydrochloric acid into the treated regenerant liquid 342, andthe resultant pH-adjusted treated regenerant liquid 342 can be recycledas fresh regenerant solution 186 when transferred by the solutiontransfer pump 230 to the regenerant solution tank 188.

A volume of precipitate 114 in the treated regenerant liquid 342 left inthe tank serves as a seeding agent to provide nucleation sites for thenext batch of treated regenerant liquid 342 to be treated in theregeneration treatment process. The impeller mixer 394 is then turned onto circulate this water while the pH adjuster 351 is added to the liquidin the tank 350. To add the pH adjuster 351, the pH-adjuster feed pump389 is energized to supply hydrochloric acid to the liquid 342, and thepH of the liquid is continuously monitored using an Endress+Hauser pHprobe in tank 350 (as shown in FIG. 3B) until the pH of the treatedregenerant liquid 342 drops to neutral to become recovered regenerantsolution 186. The impeller mixer 394 is then turned off, and themagnetic drive solution transfer pump 230 turned on to deliver recoveredregenerant solution 186 to the regenerant solution tank 188 for reuse toregenerate additional spent resin 60.

At this point in the regenerant treatment process, the recoveredregenerant solution 186 can be used in subsequent regenerations afterproper pH adjustment, seeing as the salinity has not been affectedduring this process and is at ideal levels for brining. Table II belowprovides data on the quality of the brine in typical raw untreated spentregenerant solution 100 and the treated regenerant liquid 342. It shouldbe noted that the reading of the untreated and treated spent regenerantsolution 100 and rinse water 196 from the salometer 221 was between 38and 40 degrees, which indicates a salt concentration by weight of10-10.6% (0.9-0.95 # salt/gal). This concentration is within the 10%-13%by weight recommendations of the manufacturer, therefore requiring noadditional salt to be added. Samples 1, 2 and 3 were taken fromdifferent tests using various doses of regenerant treatment composition111 comprising sodium hydroxide, calcium hydroxide and sodium carbonateto treat the spent regenerant solution 100 comprising brine only, brineand rinse combination and rinse only, respectively. It is apparentthrough the removal efficiency of several constituents that theregenerant treatment process was effective in treating the spentregenerant solution 100 to levels that exceeded “sweet” and reclaimedbrine. The “sweet” brine in this context refers to saturated brine at26.4% by weight (2.65 #salt/gal) at which point additional salt will notdissolve in the solution. The treated regenerant liquid 342, labeled“Reclaim Brine” in Table II, which is the last one-third of the rinsecycle, is captured and blended with the highly concentrated sweet brineto achieve the proper salinity strengths. Typically, the last one-thirdof the rinse cycle is predominately free of contaminants and hasmoderate levels of salinity which lends well to using it for blendingdown the “sweet” brine. However, in Table II below, it is apparent thatthe treated regenerant liquid 342 had higher hardness levels attributedto capturing the rinse water 196 too early in the process.

TABLE II TESTING REPORT Na⁺ Ca²⁺ Mg²⁺ Fe³⁺ Ba²⁺ Sr²⁺ K⁺ Mn As (g/L)(mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L) Sample 1Supernatant 53.91 12.80 0.96 BDL 0.3280 1.6500 419.81 0.0800 1.5700Filtrate 53.98 6.40 0.96 BDL 0.3960 1.5800 450.83 0.0385 0.4590 Brine27.97 8800.00 6240.00 BDL 11.2000 149.9188 366.00 1.2300 0.3780 Sample 2Supernatant 68.71 56.00 0.00 BDL 0.3280 1.5000 265.68 0.0603 1.1200Filtrate 70.16 8.00 0.00 BDL 0.2570 1.0400 281.10 0.0230 0.5680 Brine51.45 4400.00 720.00 BDL 8.3000 96.1293 234.03 0.9740 8.1000 Sample 3Supernatant 59.06 72.00 4.32 BDL 0.4920 3.8800 417.29 0.0125 0.5540Filtrate 59.41 32.00 5.76 BDL 0.9030 7.4000 397.17 0.0097 0.4370 Brine29.86 6400.00 5280.00 BDL 9.1000 102.5359 336.64 1.1200 0.5470 SweetBrine 159.39 128.00 5.28 BDL 0.1050 2.3000 BDL 4.2900 2.5300 ReclaimBrine 65.67 10000.00 1200.00 BDL 15.5000 185.7957 438.19 1.6100 0.6780Cl⁻ SO₄ ²⁻ SiO₂ Zn Cu Ni Pb Cd (g/L) (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)(mg/L) (mg/L) Sample 1 Supernatant 82.49 200.97 34.6663 1.6400 1.22000.0967 0.0489 0.0018 Filtrate 82.78 177.55 22.8969 0.5220 1.6900 0.10900.0676 0.0011 Brine 69.81 170.22 9.3941 5.0700 1.9700 0.3880 0.18700.0020 Sample 2 Supernatant 104.50 293.33 18.3175 0.6350 1.5300 0.17200.0392 0.0009 Filtrate 96.20 260.70 31.6704 0.2270 1.7100 0.0689 0.02780.0014 Brine 88.01 317.99 11.5126 1.1200 1.7500 0.3210 0.1950 0.0044Sample 3 Supernatant 90.97 396.99 4.0016 0.2280 1.3100 0.0496 0.02400.0004 Filtrate 91.47 373.12 10.9991 0.3750 1.7300 0.1110 0.0413 0.0005Brine 69.13 172.01 7.4682 2.7700 1.9600 0.4350 0.1330 0.0085 Sweet Brine248.01 214.85 8.7950 0.5610 5.0000 0.0601 0.1110 0.0079 Reclaim Brine122.94 182.95 8.5810 1.2300 3.7400 0.3960 0.0814 0.0004 Hard Alk. OH⁻HCO₃ ⁻ CO₃ ²⁻ Conduct. Temp. TOC pH (mg/L as (mg/L as (mg/L as (mg/L)(mg/L) (mS/cm) (° C.) (mg/L) Sample 1 Supernatant 6.92 35.93 805.000.0042 980.74 0.38 139.50 21.60 8.05 Filtrate 7.92 19.93 660.00 0.0413798.50 3.03 139.80 21.70 10.92 Brine 6.70 47573.77 70.00 0.0025 85.310.02 114.90 21.80 9.11 Sample 2 Supernatant 7.11 140.00 1510.00 0.00641838.91 1.08 167.40 21.80 11.52 Filtrate 7.30 20.00 1120.00 0.00991363.06 1.24 166.50 21.90 12.07 Brine 6.80 13950.82 135.00 0.0031 164.500.05 143.90 21.80 6.30 Sample 3 Supernatant 5.76 197.70 25.00 0.000330.48 0.00 150.20 21.90 6.90 Filtrate 9.84 103.61 105.00 3.4942 74.8624.05 150.90 21.80 7.56 Brine 6.60 37639.34 75.00 0.0020 91.41 0.02114.50 22.00 6.04 Sweet Brine 7.12 341.64 105.00 0.0065 127.86 0.08254.00 21.60 11.64 Reclaim Brine 6.49 29918.03 90.00 0.0016 109.70 0.02180.00 22.00 4.06 BDL: Below detection limit

The treated regenerant liquid 342 can be pH-adjusted with a pH-adjustersuch as an acid from a pH-adjuster tank 387 via ph-adjuster feed pump389. A suitable acid is hydrochloric acid. The purpose of the pHadjustment is to neutralize the relatively high pH of the treatedregenerant liquid 342 to an adjusted pH to reduce or prevent scaling andbalance the chloride ion concentration in the treated regenerant liquid342. This can either be performed in a batch type process or a compoundloop flow paced process. In the batch type embodiment, the ph adjuster351, such as the hydrochloric acid, is added until the desired pH rangeor chloride ion concentration is achieved as indicated by a pH probe orpH test strips. In the compound loop flow paced embodiment, a PLCautomatically adjusts the speed and/or stroke of a metering pump basedon the filtrate flow entering the ph-adjusting tank 350 and fine tunesthe dosage based on a real-time pH probe feedback from instrumentationin the ph-adjusting tank 350. In either embodiment, a circulation mixer,such as an impeller mixer 394 or an inline static mixer, is utilized tothoroughly disperse the acid 231 into the filtrate stream supplied tothe tank 350. Since the spent rinse water 204 is combined with spentregenerant solution 100 and spent backwash water 207 to form theregenerant waste liquid 376, excess “sweet” brine will be generated. Inthis context, “sweet” brine refers to brine that is ready forregeneration without having to add any more salt and/or dilution water.The excess quantity of “sweet” brine generated in the regeneranttreatment process can be sold separately, or treated with a distillationprocess to later be used as rinse water 196 in the regeneration processas described below. The excess, pH-adjusted treated regenerant liquid342 of brine can be stored in the regenerant solution tank 188 forrecycling and reuse.

The resin regeneration and regeneration system 80 can be manuallyoperated, or operated with one or more control devices 352 a-i and/or asystem controller 348, as described above. The control devices 352 a-ican be, for example, packaged control panels that include switches,programmable logic chips (PLC) 354, and/or hard wire relays 356, andwhich can operate independently or in conjunction with each other. Thecontrol devices 352 a-i control the regenerant recovery process in theresin regeneration system 80, and accordingly, are connected to thevarious pumps, level indicators (not shown) in the tanks and vats,valves, chemical dispensers, and other components of the system 80. Thesystem 80 can also be partially or fully automated using a systemcontroller 348 with appropriate program code 370. For example, thesystem controller 348 can include program code 370 comprisinginstruction sets that sends signals to the various valves in the piping334 to control the flow of the liquids through the system 80, such asthe regenerant solution 186, spent regenerant solution 100, treatedregenerant liquid 342, regenerant waste liquid 376, backwash water 144,and rinse water 196. The valves can include ball valves, air or vacuumvalves, or check valves. The program code 370 also has instructions setsto receive and sends signals to and from pressure gauges 187 which areused to monitor their liquid pressure in the piping 334 of the system80, and flow meters. The program code 370 also includes instruction setsto operate other components such as the chemical dispensers andsprayers.

The batch-type resin regeneration system 80 achieved excellent resultsin removing the divalent ions and other chemicals from the spentregenerant solution 100. This allows an almost complete recovery andreuse of the spent regenerant solution 100, limiting the environmentalimpact that would otherwise be caused by the disposal of spentregenerant solution containing a large amount of sodium chloride andother mineral hardness into the wastewater systems. The following TableIII reveals actual certified laboratory results for the regenerantsolution recovery system.

TABLE III Location post PH adjustment Raw Filtrate Filtrate AnalyteUnits Water (no 5 um) (5 um filt) TREATED WATER RESULTS Silicon (asSiO2) mg/L <52 <52 — Nitrate-N mg/L 0.3 0.3 — Hydroxide mg/L 0 0 —Alkalinity mg/L 163 2860 — Sodium - Total mg/L 20100 37000 — Arsenic -Total mg/L <0.020 <0.020 <0.020 Strontium - Total mg/L 68.6 <2.5 —Carbonate mg/L 163 2860 — Barium - Total mg/L 6.47 <0.2 — TotalDissolved Solids mg/L 79700 102000 98600 Fluoride mg/L <1 <1 — Chloridemg/L 49100 58300 58300 Magnesium - Total mg/L 1030 <25.0 <25.0Hardness - Total mg/L 14400 <16.6 <16.6 Manganese - Total mg/L 0.69 <0.2— Calcium Total mg/L 4060 <125.0 <125.0 Calcium Hardness mg/L 10100<12.5 <12.5 Silicon - Total mg/L <25 <25 — Bicarbonate mg/L <20 <20 —Potassium - Total mg/L 135 131 — Sulfate mg/L 237 177 51 Iron - Totalmg/L <2.5 <2.5 — TREATMENT PARAMETERS THAT LED TO TREATED WATER RESULTSABOVE Brine Strength % by wt 12 REGEN OPS Brine Strength lb salt/gal1.092 VARIABLES Brine Dose lb/cf 15 Regen Resin Volume cf 120 BriningVolume gal 1649.1 Untreated Total mg/L 14400 JAR TEST Hardness TestVolume mL 500 CaOH Dose g 3 NaOH Dose g 3 NaCO3 Dose g 13.5 TreatedTotal mg/L 10 Hardness Untreated Total mg/L 14400 FULL SCALE HardnessEQUIPMENT Batch Volume gal 1035 CaOH Dose lb 51.8 NaOH Dose lb 51.8NaCO3 lb 232.9 Treated Total mg/L <16.6 Hardness

The batch-type resin regeneration system 80 can achieve a zero liquiddischarge, which means that almost none or less than 5% of the liquidused in regeneration and recovery is discharged to drains. In fact, theresin regeneration system 80 described herein allows recovery of greaterthan 90%, or even 98% of the spent regenerant solution 100. Theregeneration system 80 reduces water consumption and saves the cost ofthe chemical compounds used in the recycled regenerant solution 100, asthey are retained in the solution while undesirable ions are removed bythe recovery process.

Resin Transfer Pump

In any of the resin regeneration and recovery systems 80 describedherein, a non-abrasive resin transfer pump 130 can be used to transferresin without excessively abrading or deforming the resin. Thenon-abrasive resin transfer pump 130 does not degrade spent resin 60 orregenerated resin 194 during pumping transfer operations because it hasmoving pumping components that can pump the resins without excessivelyabrading, deforming, or re-shaping the resin. In contrast, themechanical components of conventional pumps directly contact and applypressure to the resin to abrade or erode the resin into resin fines 166,distort its shape by flattening beads, or by changing the surface areaor porosity of the resin. The non-abrasive resin transfer pump 130 isused to transfer fresh resin 22, spent resin 60, or regenerated resin194 between the different pits, vats and tanks, of the resinregeneration and recovery system 80 using pumping components that do notabrade the spent ion exchange resin in the liquid-resin mixture.

In one version, the non-abrasive resin transfer pump 130 comprises apositive displacement peristaltic pump 79 (also known as a hose pump, orperistaltic pump) an illustrative version of which is shown in FIGS. 6Ato 6C. The peristaltic pump 79 provides a positive displacement flow ofpressurized water without the need of excess water to aid in the resinmovement. In the version shown, the peristaltic pump 79 (also known as ahose pump) comprises a housing 81 having an arcuate casing 82 that isshaped to hold a flexible tube 83 in an arcuate shape, such as U-shape(as shown), or even a C-shape or O-shape (not shown). A motor 85 powersa rotatable support 86 that is mounted at the center of radius 87 of thearcuate casing 82. Each of two spin rollers 89 a,b are mounted on axes91 a,b on the support 86, which are located at the externalcircumference of the tube 83. The motor 85 rotates the rotatable support86, which in turn rotates the two spin rollers 89 a,b freely about theirown axes 91 a,b, respectively, as shown in FIGS. 6A and 6B. The rotatingspin rollers 89 a,b compress and squeeze the flexible tube 83 againstthe arcuate casing 82 as they rotate around to squeeze forward the spentresin 60 (or fresh or regenerated resin 194) in the tube 83 from thesuction port 132 to the output port 134 of the pump 79. As the spinrollers 89 a,b turn, the part of tube 83 under compression occludes toforce the resin 60 (and added liquid such as water) to be pumped to movethrough the tube 83 as shown in FIGS. 4B and 4C. Further, as the tube 83opens to its natural state after the passing of the spin roller 89 a,bthe natural resilience of the tube 83 pulls or sucks in more liquid andresin into the tube from the suction port 132, which in turn is directedto the output port 134 and eventually the regeneration vat 140. Therollers 89 a,b can be rotated in a clockwise or counterclockwise mannerto allow the resin to move bi-directionally (i.e., in either directionthrough the pump). The resin 60 is pushed through the flexible tube 83in a pulsating manner until the desired volume of resin is transferredinto any one of the vats 140 a-c as can be seen by the sight glasswindow on the side of the vat.

A suitable peristaltic pump 79 comprises a PeriFlo Pump Model FMP60peristaltic hose pump, fabricated by Periflo Inc, Loveland, Ohio. In oneversion, the peristaltic pump 79 has a maximum flow rate of from about44 gallons per minute at 115 pounds per square inch pressure. A suitabledisplacement for the pump 79 is from about 0.83 gallons/revolution. Theoperating pressure can be from about 20 to about 300 psi, such as about115 psi. The flexible tube 83 can be a polymer tube such as a naturalrubber hose, Buna M, or Norpreen hose. The housing 81 of the pump 79 canbe made from aluminum (e.g., powder epoxy-coated aluminum), the support86 made from steel or other hard materials, and the base is also madefrom steel. The suction port 132 and output port 134 can have a diametersized from about 0.5 to about 3 inches, or even 1 inch. The pump motor85 can be a 0.5 to 4 HP motor, or even 1 HP. The pump motor 85 can beoperated at a speed of 10 to 60 rpm for example, 39 rpm speed at 60 Hz.A variable frequency drive can be used to set the speed of the motor 85.

While an exemplary version of a peristaltic pump 79 is illustrated,other versions of the peristaltic pump 79 having shoes or wipers havingother shapes instead of the spin rollers 89 a,b can also be used. Forexample, a linear-shaped casing can also be used together with linearrollers that move along the direction of the linear tube instead of acurved U-shaped casing. Also, the suction port 132 and output port 134can be reversed by reversing the polarity of a voltage applied to themotor 85.

The peristaltic pump 79 was found to be unexpectedly advantageous forpumping fragile resin 22 that cannot be pumped through conventionalpumps without breaking or tearing the resin apart. Another side benefitto the peristaltic pump 79 was the elimination of softened water whichis needed to transfer regenerated resin through conventionalinjector-type pumps. This reduces the costs of generating large amountsof softened water and the costs of regenerating associated watersoftening systems. While softened water is also used in otherapplications, changing the pump to the aforementioned peristaltic pump79 effectively reduced regeneration of water softeners in the system to2 times per month as compared with the 20 times per month needed forconventional injector-type pumps. Further, the peristaltic pump 79 pumpsresin through the flexible tube 83 without pumping components such asmoving metal parts directly contacting or touching the resin beads 24 inthe tube 83. Thus, the pump 79 also allows pumping of corrosive liquids(such as regenerant solution 186 containing brine) which would otherwisecorrode metal pump parts, without excessive corrosion of the pump.

In another embodiment, the non-abrasive resin transfer pump 130 is adifferential pressure venturi-type injector 53 (also known as an ejectoror eductor) which is placed on the discharge side of a motive flow 55,as shown in FIG. 7.

The injector 53 uses a venturi-type effect generated by a set ofconverging and diverging nozzles to convert the water pressure of amotive flow 55 to increased water velocity, which creates a low-pressurezone that draws in and entrains resin-liquid mixture containing thespent resins 60. In the version shown, the injector 53 comprises aninlet 51 comprising an inlet nozzle 54 through which the motive flow 55of fluid at high pressure is provided. The fluid can be a liquid such aspressurized water, regenerant solution, or other solutions; or apressurized gas such as steam or pressurized nitrogen. In one version, aconventional centrifugal pump 41 or other pressurized potable watersupply is used to provide a motive flow 55 comprising pressurizedliquid.

In operation, the motive flow 55 of pressurized liquid, such as water,is constricted by the inlet nozzle 54 to form a liquid jet stream 56that is directed into an injection chamber 63 at a first velocity andfirst pressure. The increase in velocity of the motive flow 55 throughthe injection chamber 63 results in a corresponding decrease inpressure, which draws fresh resin 22 or spent resin 60 through a suctionport 132 located adjacent and perpendicular to the flow direction of thejet stream 56. The pressurized liquid and resin stream 56 is then passedthrough the throat 57 of a converging-diverging nozzle 58, which createsa high pressure area at the throat 57. The pressure energy of the motiveflow 55 is converted to kinetic energy in the form of velocity head atthe throat 57 of the convergent-divergent nozzle 58. The mixed resin andliquid then enters a divergent nozzle 58 which allows expansion of thefluid jet stream in the divergent nozzle outlet 59, and thus, creates asecond pressure that is even lower than the first pressure to keep theresin 22 and liquid flowing towards the outlet 77 and the regenerationvat 140. In this manner, the resin pumping process comprises providing aflow of pressurized water; constricting a flow of pressurized liquid toform a liquid jet stream; drawing resin through a suction port adjacentto the jet stream of water; and expanding the jet stream of water tohave a second velocity and second pressure, the second velocity beinglower than the first velocity and the second pressure being lower thanthe first pressure to pump the spent resin to the regeneration vat.Typical resin transfer ratios range from 13-35 gallons of water to move1 gallon of resin. Suitable differential pressure injectors include theEductor™ from Pentair, Minneapolis, Minn., or a Mazzei® Injector fromMazzei Injector Corp., Bakersfield, Calif. The injector 53 is alsoadvantageous as it does not damage or otherwise degrade spent resin 60,especially resin beads 24, during transfer operations. The injectors 53can also be used as back-up systems in the event of failure of theperistaltic pump 79, such as a breakage in the flexible tube 83, or whenthe pump 130 needs to be replaced or removed for maintenance.

Filtering System

In any of the resin regeneration and recovery systems 80 describedabove, a solids separator 500 can be used to separate insolublematerial, such as precipitates, from a liquid such as water or othersolutions, and may comprise, for example, a filter press, centrifuge,sediment filter, or other solids separating apparatus. In one version,the solids separator 500 comprises a filter 508 that filters the treatedregenerant liquid 342 to separate out precipitate flocs 114 from thesolution.

In one embodiment, the filter 508 comprises a filter press 520 thatincludes a series of filter plates 524 which are configured to trap theprecipitate flocs 114 from a treated regenerant liquid 342 that ispumped by a pump 65 (see FIG. 5C) through the filter plates 524, asillustrated in FIGS. 8A and 8B. The filter plates 524 each comprise aframe 526 made from polypropylene or metal, and a filtering cloth 530stretched taut across the frame. The filter plates 524 are arrangedsubstantially parallel to one another, and configured to slide along apair of rails 528, so as to enable separation of the plates 524 tocreate space between the plates 524. A suitable filter press 520 is aJ-Press® from Siemens Water Technologies, Corp., Holland, Mich.

In the version shown, each filter plate 524 comprises discharge tubes526 to receive filtered fluid from the filtering cloth 530 and allowtransfer of the filtered fluid along the filter stack to the outlets512. O-rings can be provided around the periphery of the filtering cloth530 and around the discharge tubes 527 so that when the filter plates524 are pressed together, a water-tight seal is formed between theplates 524 and around the path of the discharge tubes 527. Head plate532 and tail plate 544 are pressed towards each other to maintain anactive filter stack in a water-tight state during filtering by sealingthe ends of the stack. In the embodiment shown, a back-up plate 538 andfollower plate 540 are provided behind tail plate 544 to encloseadditional filter plates 524 to maintain this second filter stack in awater-tight state during filtration. Head plate 532 comprises passagesto receive fluid from an inlet 510 and to release treated fluid from thedischarge tubes 527 to the four outlets 512 which are located at eachcorner. The filter plates 524 can be separated to remove precipitated orinsoluble material which accumulates between the filtering cloths 530 toform filter cakes 534. The accumulated filter cakes 534 can also beremoved from the plates 524 by scraping, picking, vibrating, or shakingthe plates after they are separated. The filter press 520 can optionallyinclude rinse valves and rinse fluid supply system, and air dryingvalves with air supply system (not shown) to allow further treatment ofthe filter cake 534 prior to removal. For example the filter press 520can include valves and fluid supply to supply a rinse fluid to the cake534, e.g., for chemical neutralization of the precipitated material.Alternatively, or additionally, the filter press 520 can include airdrying valves and air supply to pass air through the tubes 526, 527 ofthe filter press 520 and to enable drying of the cake 534 prior toremoval.

In another version, the solids separator 500 comprises a centrifuge 700that is adapted to centrifuge precipitate flocs 114 from a treatedregenerant liquid 342 processed in the centrifuge 700, as illustrated inFIG. 9. The centrifuge 700 comprises a bucket 702 to hold the liquid342, the bucket 702 comprising a cylindrical wall 712 having an innercircumference 703 and that encloses the liquid. The bucket 702 can be astainless steel or plastic container. A rotatable shaft 704 is mountedin the radial center of the bucket 702. The rotatable shaft 704comprises a hollow tube 705 with a plurality of openings 706, an inlet708 to receive the treated regenerant liquid 342, and an outlet 707 torelease output the centrifuged solution which is free of precipitatedcompounds of flocs. The openings 706 extend along a length of the hollowtube 705, and allow liquid 342 to pass from the inlet 708 into thehollow tube 705 and out of the openings 706 into the bucket 702. Theinlet 708 has an inlet valve 709 which can be shut off once the bucket702 is filled with liquid 342. During operation, the openings 706 alsoreceive centrifuged clean liquid from the bucket 702 which is forcedinto the openings 706, and which then passes through the hollow tube 705and out of the outlet 707. An outlet valve 711 allows clean liquid freeof precipitate flocs to flow out of the shaft 704. In one embodiment,the rotatable shaft 704 is made from a metal such as stainless steel,aluminum or titanium. The rotatable shaft 704 can also have depressionsor cut-outs to reduce the weight of the rotatable shaft 704.

A plurality of blades 710 a-d extend radially outward from the rotatableshaft 704 and have an edge 713 that terminates close to the innercircumference 703 of the cylindrical wall 712 to leave a small gap 717between the blades 710 a-d and the wall 712 of the bucket 702. Whenrotated, the blades 710 a-d impart a centrifugal force to the liquid 342in the bucket 702 that causes the liquid 342 to spin around in thebucket to force solids, such as the precipitate flocs 114 or otherparticles, toward the wall 712 of the bucket 702. During the rotationalprocess, clean liquid free of precipitates 114 is forced into theopenings 706 and into the hollow tube 705, while the inlet valve 709 isshut and the outlet valve 711 is open, causing clean liquid comprisingseparated regenerant solution 374 to flow out of the outlet 707. In theversion shown the blades 710 a-d are flat rectangular plates that arespaced apart along, and attached to, the shaft 704 and extend parallelto a rotational longitudinal axis 715 of the shaft 704. However, theblades 710 a-d can have other shapes and configurations that would causethe liquid 342 to be rotated efficiently in the bucket 702, as would beapparent to those of ordinary skill of the art. In one embodiment, theblades 710 a-d are made from a metal such as stainless steel, aluminumor titanium.

The rotatable shaft 704 is allowed to rotate about its axis using arotational system 714, such as ball bearings, fluid based bearings orother systems. In one version, the rotational system 714 comprises afirst magnetic levitation system 716 that magnetically levitates therotatable shaft 704. The magnetic levitation system 716 comprises afirst magnet 718 having a first magnetic pole 720 facing away from theshaft 704, and which hovers above a second magnetic pole 722 of a secondstationary magnet 724 which is held in place in a cylindrical base 728.The first and second magnets 718, 724 each have magnetic field strengthsthat are sufficiently strong to levitate the weight of the rotatableshaft 704 so that the shaft 704 can rotate with reduced or evennegligible frictional forces.

The rotatable shaft 704 is powered by a motor 730 which rotates therotatable shaft 704 about the longitudinal rotation axis 715 causing theblades 710 a-d to rotate and generate a centrifugal force in the liquid342 in the bucket 702. For example, the motor 730 may be a rotaryelectric motor connected to a gear assembly 734 comprising a first gear736 attached to a shaft 737 of the motor 730 which drives a second gear738 attached to the rotatable shaft 704. The motor 730 can rotate therotatable shaft 704 at a speed of from about 500 to about 50,000 rpm.

A second magnetic levitation system 740 magnetically levitates thebucket 702. The second magnetic levitation system 740 comprises acylinder 741 having a first end 742 that is attached to the wall 712,and a second end 743 attached to an annular magnet 744. The annularmagnet 744 comprises a lower face 746 a and an upper face 746 b thathave opposing polarities. A basal magnet 748 has an upward face 749 thatfaces the lower face 746 a of the annular magnet 744, and the upwardface 749 has a polarity opposite to the polarity of the lower face 746a. A top magnet 750 has a bottom face 751 that faces the upper face 746b of the annular magnet 744, and has a polarity opposite to the polarityof the upper face 746 b. The pair of basal and top magnets 748, 750 eachhave magnetic field strengths that are sufficiently strong to levitatethe weight of the bucket 702, wall 712, cylinder 741, and annular magnet744 such that the bucket 702 and its liquid contents can rotate withreduced or even negligible frictional forces.

In the resin regeneration and recovery systems 80, spent rinse water 204or other forms of wastewater which cannot be otherwise recovered can bedistilled in a distillation apparatus 328 to form distilled water 329,for example, as shown in FIGS. 10A to 10D. In one version, thedistillation apparatus 328 generates distilled water 329 from the spentrinse water 204, and the distilled water is highly pure and considered a“hungry” water, thereby wanting to bond to any available ions in thewater such as the excess salt, and accordingly, is beneficial for reuseas “softened” rinse water. The distillation apparatus 328 can be used totreat 97% of the treated water volume needed for rinsing the regeneratedresin 194, reducing the need to add make-up water from the city watersupply for rinsing. This further minimizes water consumption andprovides a closer to zero liquid discharge from the resin regenerationand recovery system 80.

The distillation apparatus 328 can use a heat source from an engineexhaust, heating elements, solar heat, or other sources to heat spentrinse water 204 or other waste liquid for distillation to form distilledwater. In one version, as shown in FIGS. 10A to 10C, the distillationapparatus 328 comprises a thermal distiller 420 connected to the exhaustgas output 422 from an engine 425 to capture the heat from the exhaustgases of the engine 425 to evaporate and recover the spent rinse water204. The engine 425 is, for example, an internal combustion engine whichgenerates electrical or motive power to operate portions of theregenerant recovery system 205. In one version, the engine 425 is adiesel engine having an exhaust pipe 444 to deliver hot exhaust gas 450from the engine 425 as shown in FIG. 10C. The engine 425 comprises anexhaust manifold 446 which collects exhaust gas 450 into an exhaust pipe444 that leads to a catalytic converter 448 and an exhaust muffler 452before venting to the atmosphere.

The thermal distiller 420 comprises a condenser housing 443 locateddirectly above a heat exchanger 445 powered by a heat source, such as ahot exhaust gas 450 of an engine 425. The condenser housing 443comprises a condenser hood 451, gutter well 456, condensed water tray458, and cooling water tray 461, as shown in FIGS. 10A and 10B. Thecondenser hood 451 can for example, have a sloped wall 428 that connectsto a sidewall 449. Part or all of the condenser housing 443 can befabricated from a thermally conductive metal, such as stainless steel orcopper.

The heat exchanger 445 comprises an inlet manifold 454 that feeds aplurality of longitudinal pipes 457 in a heat exchanger tray 447 withthe pipes 457 terminating in an outlet manifold 459 which exhausts tothe atmosphere. The heat exchanger tray 447 receives spent rinse water204 (or other wastewaters, including spent regenerant solution 100). Agas transfer pipe 453 connected upstream of the muffler 452 in theexhaust pipe 444, redirects the exhaust gas 450 to the inlet manifold454 of the heat exchanger 445. The gas transfer pipe 453 comprises anexhaust valve 455 to control the flow of exhaust gas 450 into the pipe453. In one version, the heat exchanger 445 comprises a pipe array 465of longitudinal pipes 457, each of which is spaced apart along a lengthof the inlet manifold 454 and exhaust manifold 446. In the versionshown, the pipe array 465 of longitudinal pipes 457 can include one ormore, (e.g., two) linear sub-arrays 465 a,b of the longitudinal pipes457 which are vertically spaced apart, and with each sub-array of pipes465 a,b offset from the other and stacked over each other to maximizeheat distribution to the spent regenerant solution 100. The longitudinalpipes 457 can be, for example, copper pipes having a diameter of fromabout 1 cm to about 4 cm, or even 2.54 cm (1 inch). The outlet manifold459 collects the exhaust gas 450 passing through the longitudinal pipesfor discharge through a venting pipe 460 to the atmosphere.

In operation, spent rinse water 204 or other water comprising dissolvedcompounds is delivered from the spent rinse water sump 202 to the heatexchanger tray 447 and the gutter well 456 by a discharge manifold 470comprising distiller valve 468. The gas transfer pipe 453 feeds theexhaust gas 450 into heat exchanger 445 causing the spent rinse water204 on the heat exchanger tray 447 to evaporate, rise up, and thencondense on the internal condensing surfaces of the sloped wall 428 andsidewall 449 of condenser hood 451, as shown in FIGS. 10A and 10B. Thegutter well 456 cascades spent rinse water 204 over the external surfaceof the condenser hood 451 to cool off the condensing surface. Theevaporated water that condenses on the condenser hood 451 comprisescleaned distilled water 329 and is collected in the condensed water tray458, while spent rinse water 204 used to cool the condensing surfaces iscollected in the cooling water tray 461. Distilled water 329 is thentransferred from the condensed water tray 458 to the distilled watertank 463 through distilled water piping 464. Water in the cooling watertray 461 is returned through return water piping 467 a,b to the heatexchanger tray 447 to be evaporated. The return water piping 467 a,bcomprises p-traps 466 a,b to create a water-filled sealing mechanism inthe U-shaped portion of the p-traps 466 a,b in the piping that preventssteam from escaping the heat exchanger 445, which would result in wastedheat or water. The clean distilled water 329 collected in the distilledwater tank 463 is pumped by a submersible pump 206 to the rinse watertank 198 to be used for subsequent rinsing processes. Using this system,from 800 gallons (used to rinse one batch of 120 ft³/day of regeneratedresin 194) to 1600 gallons (used for two batches of 120 ft³ ofregenerated resin 194) of spent rinse water 204 can be recycled andrecovered instead of sending this spent rinse water to the sewer.

To operate the thermal distiller 420, the engine 425 has to be inoperation, and the exhaust valve 455 on the exhaust manifold 446 isconfigured (or the exhaust piping redirected) to pass the exhaust gases450 from the engine 425 to the thermal distiller 420. Typically, theexhaust gases 450 are at a temperature of from about 300 to about 800°F. In this step, it is desirable to ensure that the exhaust flow never“dead heads” or has a flow path that causes engine damage. The heat fromthe exhaust gas 450 is transferred to the longitudinal pipes 457 of theheat exchanger 445 and exits from the thermal distiller 420 to theatmosphere. The headloss through the pipes 457 silences the exhaustnoise but does not exceed backpressure requirement on the engine 425.

When the longitudinal pipes 457 of the thermal distiller 420 are hotenough to evaporate water, the distiller valve 468 on the dischargemanifold 470 are configured to allow water to flow to the thermaldistiller 420. Also, before spent rinse water 204 in the spent rinsewater sump 202 is sent to the thermal distiller 420, a water rinse flowmeter 472 connected to the input of the spent rinse water sump 202 (or afloating water level gauge) should desirably have a reading indicatingthat from about 50 to about 100 gallons of spent rinse water 204 haspassed to the spent rinse water sump 202 to have sufficient water in thesump for distillation.

When the water in the sump 202 is at a sufficiently high level, the headof water allows the spent rinse water 204 to flow by gravity to thethermal distiller 420, and this can be done by opening the distillervalve 468 to allow the gravity flow to the distiller 420. If not, thevalves 468 on the discharge manifold 470 is configured, and asubmersible or solution transfer pump is activated to deliver eitherspent regenerant solution 100 or spent rinse water 204 to the thermaldistiller 420 for cooling the distiller 420 or for supplying thedistiller with water for distillation.

After the water commences flow to the thermal distiller 420, thedistiller valve 468 are adjusted on discharge manifold 470 to allowproper ratio of cooling water flow that drives condensation onto theexternal surfaces of the condenser hood 451 to flow cool water. At thisstage it is desirable to check if the cooling water portion of the flowis evaporating too quickly on the condenser hood 451. If so, the flowrate of cooling water to the hood surface is increased by diverting morespent rinse water 204 to the gutter well 456 as opposed to filling theheat exchanger tray 447. Conversely, if too much cooling water isdraining back into heat exchanger tray 447, then the flow of coolingwater flow onto the hood 451 is decreased by diverting more spent rinsewater 204 to filling the heat exchanger tray 447 and less to the gutterwell 456.

When the distilled water 329 accumulates in the distilled water tank 463to the high water level, a submersible pump 206 energizes to transferthe distilled water 329 to a distilled water tank 463. When all thespent rinse water 204 in the thermal distiller 420 has been treated orwhen the distilled water tank 463 is completely filled and reaches itshigh water level, the distillation process can be stopped. When solidsalt residues need to be removed from the thermal distiller 420, thecondenser hood 451 of the thermal distiller 420 is opened for scrapingoff the accumulated salts from tank 463 at the bottom of thermaldistiller 420. The condenser hood 451 is then closed and the thermaldistiller 420 ready to treat the next batch of spent rinse water 204.

In another version, the distillation apparatus 328 comprises a heatingelement (not shown), such as an immersion heater or a pipe heaterlocated in the tank to heat the water in the tank. The hearing elementcan be powered by electricity and can be a resistive heater, such as acoil of nichrome or other resistor material. In still another example,the distillation apparatus 328 comprises a renewable heat source, suchas, for example, solar power heated oil which is heated in tubespositioned at the focal point center of longitudinal convex, forexample, parabola, shaped reflective surfaces (such as mirrors) orpolished steel.

Advantageously, when the spent rinse water 204 contains salts washedaway from the resins, less heat is required to evaporate the water, andconsequently, precipitate the dissolved salts in the spent rinse water204. For example, rinse water containing a sodium chloride concentrationof from about 10 wt % to about 13 wt % has lower BTU requirements toevaporate because the dissolved salt reduces the specific heat of thesolution, which also decreases the KW-hr per temperature increase ratio.Also, another advantage is that heating the spent rinse water 204decreases the calcium solubility constant, thereby precipitating calciumcarbonate at the bottom of the tank vessel similar to the scaling thatoccurs on a hot water heater heating element. This effect can alsoreduce the amount of calcium hydroxide and sodium hydroxide needed toprecipitate the same calcium carbonate. In this manner, the thermaldistiller 420 provides an efficient method of distilling water usingwaste heat from an engine 425 or other heat source.

EXAMPLES

The following examples are provided to illustrate exemplary embodimentsof the present apparatus and process. However, these examples should notbe used to limit the scope, applicability or configuration of theinvention. Instead, the examples are intended to provide illustrationsfor implementing various embodiments of the invention. As will becomeapparent, changes may be made in the function or arrangement of any ofthe compounds, methods, steps, or apparatus described in the disclosedexemplary embodiments without departing from the spirit and scope of theinvention.

Example 1 Composition of Spent Regenerant Solution

To determine the composition of an exemplary regenerant solution 186 asit is passed through spent resin 60, samples of regenerant solution 186were taken out of a regeneration vat 140 at specific time intervalsduring treatment of spent resin 60 with regenerant solution 186comprising brine. In this example, a small test vat (not shown) wasfilled with spent resin 60 and then regenerant solution 186 added to thespent resin 60. The regenerant solution 186 was re-circulated throughthe test vat for 50 minutes, followed by a 30 minute rinse of thetreated resin 60 with water to remove regenerant solution residue, andthen a secondary and final rinse of the treated resin was done withsoftened water.

Samples of the spent regenerant solution 100 and spent rinse water 204were taken from the test vat during recirculation of the regenerantsolution 186 at 10 minute intervals in the resin regeneration process.These samples were chemically analyzed to determine the composition ofthe regenerant solution 186 over time as it regenerates the spent resin60, as shown in Table IV. The regenerant solution samples mostlycontained sodium chloride dissolved in water, but also contained manyother dissolved ions extracted from the spent resins 60 such as Ca⁺²,Mg⁺², Fe⁺², Ba⁺², Sr⁺² and other ions in trace amounts. Also, samples ofsoftened rinse water passed through the regenerated resin 194 (afterremoval of the regenerant solution 186) became clean rinse water,indicating all the salt and other regeneration compounds had been rinsedout of the regenerated resin 194, after between 60 and 70 minutes. Afterthis time most of the divalent ions were removed from the spent resin60. Thus, after initially rinsing for 60 minutes, the remaining spentrinse water 204 can be reused without extensive recovery processing.

To evaluate a consistent composition of the spent regenerant solution100 to determine the regenerant composition that would serve toregenerate the spent regenerant solution 100, a composite sample (Comp)was prepared by mixing together seven samples, each of which was takenat a specific time separated by ten minute intervals and in the first 70minutes of a spent resin regeneration process. It should be noted thatthe composite sample was not taken over the entire 100 minute cycle soas not to dilute the composite sample with relatively ‘clean’ rinsewater.

The water quality of the composite sample from Table II was alsocompared to the water quality evaluated during the bench testing. Thecomparison shows that there is a slight difference in water quality withrespect to the major concentrations of ions between the different resinregeneration cycle samples.

TABLE IV Sampling Time (min) 10 20 30 40 50 60 70 80 90 100 Comp. pHunitless 7.31 6.29 6.4 6.58 6.7 6.76 7.1 7.68 8.04 8.44 6.96 Na g/L 1.4637.33 52.73 55.89 48.66 29.14 29.97 6.05 2.78 0.89 29.12 Ca mg/L 25.548607.03 9466.89 5085.09 3426.91 2546.43 1284.72 83.72 22.34 17.572949.21 Mg mg/L 10.63 2192.08 2586.05 773.86 589.97 371.71 166.18 12.944.26 1.27 971.06 Fe3 mg/L <0.01 0.03 0.04 0.04 0.02 <0.01 <0.01 <0.01<0.01 <0.01 0.02 Ba mg/L 10.17 164.54 167.53 83.77 53.85 41.88 17.95 <5<5 <5 107.7 Sr mg/L <6 <74 <90 <51 <33 <23 <13 <6 <6 <6 <34 K mg/L <19<100 <177 <176 <93 <70 <40 <7 <3 <1 <42 Cl g/L 1.58 60.45 91.16 87.3075.41 69.84 45.63 8.60 2.74 1.02 52.18 F mg/L 0.71 2.16 2.51 4.29 3.532.51 2.96 1.62 1.53 0.47 3.23 SO4 mg/L 598.04 664.49 697.87 819.5 675.77479.66 566.18 582.3 551.26 541.84 617.69 NO3 mg/L <5 <50 <60 <59 <53 <43<30 <6 <2 <1 <30 SiO2 mg/L 10.07 4.71 4.89 5.53 5.32 5.53 7.58 9.7410.28 10.61 8.02 Hard. mg/L as 107.41 30501.50 34265.81 15884.2810985.19 7889.45 3892.87 262.35 73.30 49.14 11352.77 CaCO3 Alk. mg/L as160 80 90 110 90 120 140 170 170 140 100 CaCO3 OH mg/L as 0.01 0.0010.001 0.002 0.003 0.003 0.006 0.024 0.055 0.138 0.005 CaCO3 HCO3 mg/L194.82 97.58 109.77 134.15 109.75 146.32 170.59 206.45 205.23 166.35121.89 (Calc.) CO3 mg/L 0.18 0.01 0.01 0.02 0.03 0.04 0.1 0.45 1.04 2.110.05 (Calc.) Cond. mS/cm 6.61 156.2 184.6 182.1 169.7 162.4 111.2 26.89.4 3.9 111 Turb. NTU 0.671 1.541 1.686 0.901 0.418 1.133 0.997 1.0890.463 0.801 0.536 Temp C. 19.68 19.23 19.31 19.31 19.12 19.36 19.2119.17 19.29 19.42 19.12 TOC mg/L 2.55 3.57 4.46 4.97 5.06 4.63 7.53 4.114.79 4.09 4.15 DO mg/L 9.64 5.6 5.22 5.33 5.46 5.46 5.72 8.65 9.2 9.345.78

TABLE V Composite Spent regenerant solution 100 Samples Batch I Batch IIpH 6.96 6.8 Sodium g/L 29.12 50.02 Calcium mg/L 2949.21 4906.68Magnesium mg/L 971.06 1623.49 Iron (III) mg/L 0.02 0.0314 Barium mg/L107.7 6.11 Strontium mg/L <34 53.4 Potassium mg/L <42 99.0099 Chlorideg/L 52.18 50.02 Flouride mg/L 3.23 BDL Sulfate mg/L 617.69 552.06Nitrate mg/L <30 BDL Silica mg/L 8.02 13.8237 Hardness mg/L as CaCO311352.77 18920.33 Alkalinity mg/L as CaCO3 100 70 Hydroxide mg/L asCaCO3 0.005 0.0032 Bicarbonate mg/L (Calc.) 121.89 85.35 Carbonate mg/L(Calc.) 0.05 0.02 Conductivity mS/cm 111.1 111.5 Temperature C. 19.1223.9

Table V shows the water quality of samples taken to compare thecomposite samples of spent regenerant solution 100. It is seen that thebarium concentration is dramatically different in the two compositecycles that were sampled from spent regenerant solution 100 that wasextracted from regeneration processes conducted on ion exchange resins22 at different times of the year, namely, April and July. While thisdiscrepancy is not immediately explainable, the treatment and recoveryprocess for the spent regenerant solution 100 would have to account fortreatment of a range of solutions that includes these two compositesample compositions. Further, the solids content as represented by thesilica levels are similar, which suggests the similarity in compositionof potable water sources for the different areas. The alkalinity of bothsamples is very low relative to the total hardness, indicating thatnearly all the hardness results from non-carbonate compounds. Further,the spent regenerant solution 100, as shown in Tables IV and V above,has a significant amount of calcium, barium and magnesium, which resultsin a high mineral hardness value in water.

Example 2 Regenerant Treatment Composition

Once the composition of some samples of different spent regenerantsolutions 100 was evaluated, different compositions of the regeneranttreatment compositions 111 were tested to treat and regenerate the spentregenerant solution 100 and to treat regenerant waste liquid 376comprising spent regenerant solution 100 as well as other liquids, suchas the first 50 gallons to 100 gallons of spent rinse water 204. Inthese experiments, a bench test was performed by filling a jar with thecomposite sample of the spent regenerant solution 100 as outlined aboveand treating the composite liquid sample with regenerant treatmentcomposition 111 to regenerate the solution. In this test, a regeneranttreatment composition 111 comprising a first regenerant composition 111a composed of calcium hydroxide (also known as lime or slaked lime) anda second regenerant composition 111 b composed of sodium carbonate (alsoknown as soda or soda ash) was added to each test jar. Calcium hydroxidewas selected primarily to precipitate magnesium ions from the spentregenerant solution 100 in the form of magnesium hydroxide, and sodiumcarbonate was selected primarily to precipitate calcium ions from thespent regenerant solution 100 in the form of calcium carbonate.

The bench test was conducted to determine the dose rates for regeneranttreatment compositions 111 comprising calcium hydroxide and sodiumcarbonate and also to measure the composition of the treated regenerantliquid 342 achievable through this process. Specifically, thecomposition of the treated regenerant liquid 342 was used to determinethe percent removal of strontium, barium, calcium, magnesium andhardness, for increasing molar concentrations of calcium hydroxide andsodium carbonate, and the dose of hydrated calcium hydroxide and sodiumcarbonate needed to remove most of the undesirable calcium and magnesiumions in the treated regenerant liquid 342, allowing for reuse of thetreated regenerant liquid to regenerate spent ion exchange resin 22, wasalso determined.

Table VI shows the results of adding a regenerant treatment composition111 a,b comprising adding first calcium hydroxide (Ca(OH)₂), and thensodium carbonate (Na₂CO₃) to the spent regenerant solution 100,sequentially. The first block of the table refers to tests in which nosodium carbonate was added and varying amounts of calcium hydroxide wereadded in the form of slaked lime. The calcium hydroxide was added toincrease the pH to a level that would allow precipitation of all themagnesium ions in the form of magnesium hydroxide. Based on themagnesium removal rates, an optimum calcium hydroxide dose of 67 mM ofcalcium per liter of spent regenerant solution 100 was selected. Thefirst half of the Table IV shows the results of bench tests in which 67mM calcium hydroxide was added and varying amounts of sodium carbonateranging from 67 mM to 217 mM were added to establish the dosage neededfor complete removal of calcium from the solution 100. Based on theseresults, good calcium removal can be achieved with a sodium carbonatedosage of from about 2 to 3.25 times the addition of calcium hydroxidein moles. Thus, a calcium hydroxide addition molar of 3×(200 mM) waschosen for subsequent experiments.

TABLE VI Sample Chemical Addition Final Concentration pH Na2CO3 HardnessLime Added Ca Added Total Ca Added mg/L as Ca Mg mg/L mg/L mM mg/L mMmg/L mM CaCO3 mg/L mg/L Lime Test Brine Composite 6.8 0 0.00 0.004720.00 117.77 0.00 0.00 17702 4720 1440 Lime to Achieve pH 9 158 85.192.13 4805.19 119.90 0.00 0.00 17711 4960 1296 Lime to Achieve pH 9.5 203109.54 2.73 4829.54 120.50 0.00 0.00 17518 5040 1200 Lime to Achieve pH10 270 146.05 3.64 4866.05 121.41 0.00 0.00 17121 4960 1152 Lime toAchieve pH 10.5 4275 2312.41 57.70 7032.41 175.47 0.00 0.00 16780 6240288 Lime to Achieve pH 11 4950 2677.53 66.81 7397.53 184.58 0.00 0.0016800 6720 0 (Optimized) Lime to Achieve pH 11.5 5400 2920.94 72.887640.94 190.65 0.00 0.00 17600 7040 0 Soda Test Soda = 1 × OptimizedLime 11 4950 2677.53 66.81 7397.53 184.58 66.81 7080.97 9393 3600 96Soda = 1.5 × Optimized Lime 11 4950 2677.53 66.81 7397.53 184.58 100.2110621.46 4990 1760 144 Soda = 2 × Optimized Lime 11 4950 2677.53 66.817397.53 184.58 133.62 14161.95 997 320 48 Soda = 3.25 × Optimized Lime11 4950 2677.53 66.81 7397.53 184.58 217.13 23013.16 8 0 2

Based on these results, it was determined that treating the spentregenerant solution 100 with the regenerant treatment composition 111reduced the concentration of most of the divalent ions to less than 80%of the original concentrations, or even less than 90%, or even less than98%. However, silica was left in the treated regenerant liquid 342 at aconcentration of less than about 2 mg/L and sulfate salts were left at aconcentration of less than about 270 mg/L, and some zinc was also in thesolution, the presence of zinc being unusual and which may have resultedfrom contamination.

While it was observed that the magnesium ions were removed from thespent regenerant solution 100 by the addition of calcium hydroxide untilthe spent regenerant solution 100 achieved a pH level of about 11.However, the magnesium levels in the composite sample of the spentregenerant solution 100 for the addition of sodium carbonate show highermagnesium levels at a pH level of about 11. It was noted that magnesiumremoval was not as high because the pH was not raised as much aspredicted (namely to 11) by the calcium hydroxide addition. Thus, ahigher dosage of calcium hydroxide of up to about 70 mM would beexpected to decrease magnesium content to below detectable levels, aswell as decrease the overall hardness of the treated regenerant liquid342 to approximately 40 mg/L CaCO₃.

Thus, an exemplary regenerant treatment composition 111 comprisescalcium hydroxide added in a molar ratio of calcium hydroxide to spentregenerant solution 100 of at least about 25 mM of calcium per liter ofspent regenerant solution, or even from about 30 to about 120 mM ofcalcium per liter. Another exemplary regenerant treatment composition111 comprises sodium carbonate added in a molar ratio of sodiumcarbonate to spent regenerant solution 100 of at least about 50 mM ofsodium per liter of spent regenerant solution, or even from about 60 toabout 360 mM of sodium per liter. Other concentrations can also be usedand should be sufficiently high to remove at least about 80% of thecalcium ions from the spent regenerant solution 100. One exemplaryregenerant treatment composition 111 comprises calcium hydroxide in aconcentration of 70 mM and sodium carbonate in a concentration of 210mM. This composition was calculated to reduce magnesium content to belowdetectable levels and also improve the hardness of the solution.Typically, a further reduction in magnesium ions in the spent regenerantsolution 100 correlates with greater removal of silica, so a decrease ofsilica content to about 2.0 mg/L might also be expected.

Example 3 Solids Dewatering

Solids dewatering tests were performed using a bench-scale filter press520, comprising a plate 524 and frame 526 mechanism, to extract waterand characterize the amount of solids that could be expected in theextracted precipitates, which are in the form of filter cakes 534, todetermine the composition of the material and if it could be sent to alandfill. The test results, as shown in Table VII, reveal thatprecipitates 114 contain large amounts of calcium hydroxide and thatthese materials are typically easy to concentrate to high levels. Thefilter cake 534 was generated by operating the filter press 520 at apressure of 80 psi.

TABLE VII SAMPLE DESCRIPTION RESULTS Solids Content of Sample 13.75percent Water Content of Sample 86.25 percent Solids Content of FilterCake 49 percent Water Content of Filter Cake 51 percent

A toxicity test was then performed to determine relative toxicity of thesolids to confirm if they can be disposed of to a landfill, as shown inTable VIII. It is clear from the test that the precipitate 114 from thefilter cakes 534 has a high solids content and can be classified asnonhazardous waste material suitable for ordinary landfills. Therefore,it is anticipated that the solids could be disposed of in any normallandfill.

TABLE VIII Leaching Test EPA Regulatory Landfill Aqueous HW CAS LevelTCLP WET Leachate Solubility No.¹ Contaminant No.² (mg/L) (mg/L) (mg/L)(mg/L) (mg/L) D004 Arsenic 7440-38-2 5 0.004410 0.013800 0.0129000.006600 D005 Barium 7440-39-3 100 0.030100 0.025400 0.003180 0.009570D006 Cadmium 7440-43-9 1 0.000010 0.000150 0.000350 0.000010 D008 Lead7439-92-1 5 0.000030 0.001210 0.000500 0.000230 Silica (SiO2) NAL1.744903 51.64409 15.19768 0.428993 Manganese NAL 0.000070 2.1069320.000270 0.000390 Nickel³ 1,000 0.000575 0.017300 0.053900 0.000452Copper⁴ 100 0.025700 0.110364 0.044600 0.023100 Zinc NAL 0.0026400.091842 0.014400 0.002060 Strontium NAL 0.473081 0.293663 0.0891000.083800 ¹Hazardous waste number. ²Chemical abstracts service number.³10X MCL under considered as surrogate regulatory limit ⁴100X Secondarydrinking water standard as surrogate regulatory limit NAL: no actionlimit

Example 4 Nanofiltration Membrane

Optionally, the treated regenerant liquid 342 can be passed through asolids separator 500 comprising a particle filter 184 which is ananofilter 410, an exemplary embodiment of which is shown in FIGS. 11Aand 11B. The nanofilter 410 comprises a housing 409 holding asemipermeable membrane through which fluid, such as the treatedregenerant liquid 342 and monovalent ions 419 ion solution in the fluid,will pass but which blocks the passage of multivalent ions 424 and otherimpurities. Typically, the nanofilter 410 comprises a semipermeablemembrane that is spirally wrapped several times to form layers about aperforated central tube 412 having holes 408, with the semipermeablemembranes separated by a plurality of feed solution spacers 413.Typically, the nanofilter 410 further comprises a feed solution input414 which is at the top of and between the membranes, a concentrateoutput 415 which is at the bottom of and between the membranes, and afiltered liquid output 416 which is the bottom outlet of the tube 412.

The semipermeable membrane is permeable to fluid and monovalent ions 419but restricts the passage of multivalent ions 424 and low molecularweight organics and salts. The feed solution spacers 413 create a spacebetween the layers of semipermeable membrane that allows for the flow offluid through the nanofilter 410 and across the surface of thesemipermeable membrane. Typically, the feed solution spacers 413separate the semipermeable membrane by from about 0.025 in to about0.100 in, creating space for fluid to flow along the length of thenanofilter 410 and across the surface of the semipermeable membrane.

Solution such as the treated regenerant liquid 342 is admitted to thenanofilter 410 through the feed solution input 414, which communicatessolution to the space between the layers of semipermeable membrane. Whenpressure is applied to the solution, fluid and monovalent ions 419 passthrough the semipermeable membrane to form the filtered liquid 417,leaving the multivalent ions 424 and other impurities, such as solids,behind to form concentrate 418. Filtered liquid 417 passes throughperforations in the central tube 412 and exits the nanofilter 410through filtered liquid output 416, while concentrate 418 is retainedoutside of the central tube 412 and exits the nanofilter 410 through aconcentrate output 415. The filtered liquid 417 can then be passed tothe regenerant solution tank 188 (in FIG. 3B) as the filtered liquidsolution should have a similar composition to the chemically treatedfiltrate after pH adjustment.

In one version, the nanofilter 410 can also be used further reduce theconcentration of undesirable ions in the treated regenerant liquid 342to generate clean water for backwashing, rinsing, or flushing. Inanother version, the nanofilter 410 is used to remove divalent ions(such as Ca⁺², Mg⁺²) from the regenerant solution 186 to generate aclean output solution—comprising sodium, potassium, or other monovalentions 419—that can be reused. The latter version allows the monovalentions 419, such as sodium and chloride ions, to remain in solution.However, the nanofilter 410 may not operate efficiently wherein thetreated regenerant liquid 342 has high salinity levels. Thus, this stageis optional.

In one version, modeling studies suggested that barium and strontium ionlevels in the spent regenerant solution 100 were too high to achievereasonable recovery of a regenerant solution comprising sodium andchloride ions. Further, the output of the computer models was notentirely trusted due to the limited ability of the modeling programs tomodel regenerant solutions having a high ionic strength. Additionally,it was apparent that the output water would still have a significantamount of divalent ions which would limit the viability of long-termreuse of the recovered solution.

In the following example, a nanofilter 410 was used to determine therejection characteristics and operation conditions for nanofiltration ofa treated regenerant liquid 342. The objectives of this test were toestablish the rejection of the nanofiltration membrane 411 for divalentions and to determine operating pressure and specific fluxcharacteristics of nanofiltration membranes for regenerant solution 186.

A bench jar sample produced by adding regenerant treatment composition111, comprising calcium hydroxide and sodium carbonate, to a jarcontaining a composite spent regenerant solution 100, was used to testthe ability of a nanofiltration membrane 411 to remove remaining ionsand/or solids. Specifically, the treated regenerant liquid 342 contained67 mM calcium hydroxide and 200 mM sodium carbonate. The nanofilter 410operates by rejecting specific ions and allowing others to pass throughthe membrane 411. This test was conducted on five different samples ofnanofiltration membranes 411. The water quality of a composite sample ofspent regenerant solution 100, the composite regenerant solution sampletreated with a regenerant treatment composition 111, and the filteredliquid output 416 from five (5) different nanofiltration membranes 411from Dow Chemical, Hydranautics, and Koch Companies, are shown in TableIX.

TABLE IX Regenerant Regenerant Soln. Treated Solution with Lime- DowNF-270- Dow NF-90- Hydranautics Koch Koch Constituent units CompositeSoda 4040 4040 ESNA1-LF* TFC SR-2 TFC-S pH 6.8 10.84 10.45 10.55 10.2910.12 10.61 Sodium g/L 50.02 39.32 36.78 37.11 33.83 38.58 35.6 Calciummg/L 4906.68 BDL BDL BDL BDL BDL BDL Magnesium mg/L 1623.49 14.88 8.1612.48 14.88 12.48 8.64 Iron (III) mg/L 0.0314 BDL BDL BDL BDL BDL BDLBarium mg/L 6.11 0.0471 0.193 0.142 0.176 0.242 0.131 Strontium mg/L53.4 0.11 0.0812 0.068 0.0656 0.0797 0.0702 Potassium mg/L 99.0099 BDLBDL BDL BDL BDL BDL Chloride g/L 50.02 39.32 36.78 37.11 33.83 38.5835.6 Flouride mg/L BDL BDL BDL BDL BDL BDL BDL Sulfate mg/L 552.06 268.167.56 161.69 67.56 131.09 106.27 Nitrate mg/L BDL BDL BDL BDL BDL BDLBDL Silica mg/L 13.8237 2.9531 0.9116 0.5478 0.3595 0.5842 0.1192Hardness mg/L as 18920.3 60.98 33.44 51.15 60.98 51.15 35.41 CaCO3Alkalinity mg/L as 70 2090 970 1270 770 810 970 CaCO3 Hydroxide mg/L as0.0032 34.2744 13.9306 17.5376 9.8394 6.637 20.1823 CaCO3 Bicarbonatemg/L 85.35 338.34 323.43 356.91 326.44 437.21 242.63 (Calc.) Carbonatemg/L 0.02 1067.04 414.58 575.95 295.55 267 450.57 (Calc.) ConductivitymS/cm 111.5 97.2 92 90.6 86.1 94.6 91.7 Temperature C. 23.9 25 25 25 2525 25

Some observations of the feed and filtered liquid water quality are asfollows. The barium content appears inaccurate for treated brine as itshould be about 0.4 mg/l, and the values for the ESNA1 filtered liquid417 are low throughout, including with sodium and chloride. It wasrealized that an in-line cartridge filter in the nanofilter 410 had notbeen drained prior to the test and after clean water rinsing, causingresidual water from the cartridge to dilute the influent regenerantsolution 186 as it was cycled through the nanofilter 410. Thus, thevalues reported in TABLE VII are measured with the caveat that a 15 to20% volumetric dilution of the influent regenerant solution depressedthe filtered liquid measurements.

In addition to water quality, the operating performance of a nanofilter410 was compared through two different tests. The first test was run toverify performance of the nanofilter 410 with a spent regenerantsolution 100 similar to conventional tests to compare operating datawith manufacturer data. Table X shows the hydraulic and salt rejectionresults of the nanofiltration membranes 411 based on trials run withinfluent feed of 2 g/L MgSO₄ and with chemically softened brine. Thefiltered liquid flux is in L/m² of membrane per hour (LMH). At the samepressure, the Koch 4092S, Filmtec NF-90-4040 and the HydranauticsESNA1-LF-4040 were higher rejecting membranes, consistent with theirspecifications.

TABLE X Koch Koch Filmtec Filmtec ESNA1-LF- Parameter units 40 92S4720SR2 270-4040 90-4040 4040 Feed Flow mL/min 830 830 830 830 830Filtered mL/min 9.02 19.03 13.64 8.88 7.07 liquid Flow Feed psi 73 73 7373 73 Pressure Concentrate psi 67 67 67 67 67 Pressure Membrane cm2137.75 137.75 137.75 137.75 137.75 Area Filtered LMH 39.28 88.88 59.3938.68 30.80 liquid Flux Feed mS/cm 2.29 2.3 2.3 2.29 2.31 ConductivityFiltered mS/cm 365 478 456 256 165.3 liquid Conductivity Rejection %84.06% 79.22% 80.17% 88.82% 92.84% Net Driving psi 70 70 70 70 70Pressure

A second test was run by passing softened spent regenerant solution 100through the nanofiltration membrane 411, as shown in Table XI.

TABLE XI One Reactor Two Reactors in Parallel Dow NF270- KochHydranautics Dow NF90- Koch Parameter units 4040 TFC-SR2 ESNA1-LF 4040TFC-S Feed Flow mL/min 830 830 830 830 830 Filtered mL/min 8.3 8.3 1.80.84 2.47 liquid Flow Unit 1 Feed psi 82 71.5 96 98 100 Pressure Unit 1psi 76 65.5 85 87 94 Concentrate Pressure Unit 2 Feed psi 85 87 94Pressure Unit 2 psi 79 80 83 Concentrate Pressure Membrane cm2 137.75137.75 137.75 137.75 137.75 Area Filtered LMH 36.15 36.15 3.92 1.83 5.38liquid Flux Feed mS/cm 95.4 97.3 93.5 97 97.7 Conductivity Filteredliquid mS/cm 92 94.6 86.1 90.6 91.7 Conductivity Temperature C. 25 25 2525 25

Observations include constant feed flow rates for all nanofiltrationmembranes 411 with the objective of the filtered liquid flow test tomaintain a constant flux rate of 36 l/m2/hr, such as that obtained withthe Dow NF-270 and Koch TFC-slow rinse2 membranes. This would be normalflow rate for operating systems and is important because water qualitycomparisons can only be made in comparison to real operating systems.The feed pressure is at the maximum of the system for HydranauticsESNA1, Dow NF-90 and Koch TFC-S membranes. This meant that the actualfiltered liquid flux was not maintained at 36 as was noted since thepressure limitations of the system would not allow the system to operateabove 100 psi of feed pressure. Therefore, the filtered liquid flux ison the order of one tenth of the real operating flux. Further, thefiltered liquid conductivity reflects the fact that the flow was notmaintained for the Hydranautics, Dow NF-90 and Koch TFC-S membranes. Theexpected filtered liquid conductivity would be much lower for theproducts if operated at a higher flux rate.

Thus, the filtered liquid fluxes of regenerant solution 186 through thenanofiltration membranes 411 are significantly decreased by the highionic strength of the regenerant waste solution or regenerant wasteliquid which translates into higher feed pressure that is not available.However, the Koch Slow Rinse2 and Dow (Filmtec) 270-4040 produced areasonably high filtered liquid flux at a pressure below 110 psi.

Estimated water quality results based on operation at normal operatingvalues with flux rates around 25-36 LMH would have improved the finalproduct quality by a factor of 3-5 thereby reducing the salinity of theproduct water. The results, even if operated properly may still limitthe selection of the nanofiltration membrane 411 as part of the process.

Example 5 Solids Separator Testing

In this example, a solids separator 500 was evaluated in the treatmentand recovery of regenerant waste liquid 376. The regenerant waste liquid376 can be any of spent regeneration solution 100 only, spent rinsewater 204, or all of the spent regenerant solution 100, spent rinsewater 204 and spent backwash water 207. The solids separator 500 treatsthe regenerant waste liquid 376 with a regenerant treatment composition111 and removes precipitated compounds 114 containing multivalent ions424 from the treated regenerant liquid 342.

In the first step, spent resin 60 is regenerated in a regeneration vat140 using fresh regenerant solution 186. Regeneration of the spent resin60 involves two stages, each of which produces spent regenerant solution100 having significantly different compositions. In the first down-flowregeneration stage, the spent resin 60 was contacted with a freshregenerant solution 186 comprising brine—specifically, a solution ofsodium chloride dissolved in water in a concentration of from about 5 toabout 15 wt %—at a dosage rate of from about 10 to about 20 lbs of NaClper cubic foot of spent resin 60. In the second down-flow rinse stage,regenerant solution 186 was rinsed off the regenerated resin 194 withrinse water 196. The rinse stage can involve both slow and fast rinsephases.

1. Characterization of Liquid Samples

The solids separator 500 was evaluated on each of three types ofregenerant waste liquid 376, namely, spent regenerant solution 100comprising brine only, spent rinse water 204 only, or a combination ofthe two. Three samples were taken for each type of liquid, namely:

(1) “brine” which indicates the regenerant solution was a liquid sampleof the influent to the treatment and recovery process;

(2) “supernatant” which was a liquid sample of the supernatant from thefilter press 520 after treatment and pH adjustment; and

(3) “filtrate” which was a solid/liquid sample of the filtrate producedafter filtration dewatering of the sludge and pH adjustment.

In addition, fresh regenerant solution 186 (“sweet brine”) and reclaimedsamples used in the resin regeneration process (“reclamined samples”)were also analyzed. These eleven liquid samples were used as a baselinefor comparison.

Table XII shows the results of chemical analysis of major species in theeleven liquid samples. Note that the pH of each sample is the valueafter depressing the level with hydrochloric acid after completion oftreatment and filtration processes. The data suggested that treatment ofall the different types of regenerant waste liquid 376 were effectiveand, in each case, greater than 99% of the multivalent ions 424 in theliquid 376 were removed in both the supernatant and filtrate:

TABLE XII Major Species Composition of Phase I Liquid Samples HardnessCl⁻ SO₄ ²⁻ Na⁺ Ca²⁺ Mg²⁺ (mg/L as TOC (g/L) (mg/L) (g/L) (mg/L) (mg/L)CaCO₃) pH (mg/L) Brine Only Supernatant 82.49 200.97 53.91 12.80 0.9635.93 6.90 8.05 Filtrate 82.78 177.55 53.98 6.40 0.96 19.93 7.90 10.92Brine 69.81 170.22 27.97 8800.00 6240.00 47573.77 6.70 9.11 Rinse OnlySupernatant 104.50 293.33 68.71 56.00 0.00 140.00 7.10 11.52 Filtrate96.20 260.70 70.16 8.00 0.00 20.00 7.30 12.07 Brine 88.01 317.99 51.454400.00 720.00 13950.82 6.80 6.30 Brine + Rinse Supernatant 90.97 396.9959.06 72.00 4.32 197.70 5.80 6.90 Filtrate 91.47 373.12 59.41 32.00 5.76103.61 9.80 7.56 Brine 69.13 172.01 29.86 6400.00 5280.00 37639.34 6.606.04 Sweet Brine 248.01 214.85 159.39 128.00 5.28 341.64 7.10 11.64Reclaimed Brine 122.94 182.95 65.67 10000.00 1200.00 29918.03 6.50 4.06

Further, with respect to removal of calcium divalent ions in the form ofcalcium carbonate, in general, water with less than 80-100 mg/L CaCO₃hardness is considered sufficiently soft to be used for strong cationexchange resin regeneration. The treatment of regenerant waste liquid376 comprising spent regenerant solution 100 or “brine only” achievedthis target, whereas treatment of the “rinse only” and combined“brine+rinse” liquids achieved this target only for the filtrate of the“rinse only” liquid. This was not expected, as the “brine only” liquidhas the highest ion concentrations initially, and would thus be expectedto provide the most challenge to soften to lower levels. However, itshould be noted that, depending on overall economic considerations,waters with hardness as high as 250 mg/L CaCO₃ may be used forregeneration of spent resins 60, with only a small loss in recoveredresin capacity; thus, in effect, the calcium ion removal was sufficient.

Magnesium hardness removal was very effective for all types ofregenerant waste liquid 376, indicating that the pH increase andstability achieved in the solids separator 500 were good. Most of thevariability in treatment efficiency came with removal of calciumhardness, suggesting that sodium carbonate dosing and/or mixing neededto be optimized. However, note that all the types of regenerant wasteliquid 376 were low in carbonate hardness; thus, nearly all calciumremoval is dependent on carbonate addition.

The pH of the combined “brine+rinse” filtrate sample was not adequatelyadjusted down to near neutral by the treatment and filtration process.This may be anomalous, but all of the filtrate sample pH values weresomewhat above their counterpart supernatant and brine values. Thisshould be checked if it is indicative of a need for better processcontrol of pH readjustment after treatment sludge dewatering.

The total organic carbon content (TOC) of all samples was sufficientlylow as not to cause a concern with resin fouling or excessive microbialstimulation. However, if the TOC levels were a concern, it can beremoved with an anionic resin such as MEIX.

The hardness, both magnesium and calcium, of the reclaimed brine iscause for concern. If this brine is used for regeneration (after sodiumaddition to meet resin manufacturer's specifications), there would besignificant loss of regenerated resin 194 exchange capacity. Althoughthe cause cannot be definitively identified, it is likely that theprocess for reclaiming brine is prematurely scavenging water from theregeneration process. The reclaimed brine had approximately double thehardness of the “rinse only” regenerant waste liquid 376, which suggeststiming and control of the water scavenging process needs examination.This reveals the importance of appropriately timing when to scavenge thebrine vs. rinse stream. If the last portion of the rinse stream iscaptured too early in the process, the operator runs the chance ofcapturing the elevated hardness levels in the brine.

The sweet brine hardness is higher than would normally be recommended,although not as excessive as for the reclaimed brine. If achievingmaximum recovery of resin capacity during regeneration is a highpriority, it would likely be economically advantageous to investigatewhy the pre-treatment of the water used for sweet brine production isnot achieving lower hardness levels.

Chemical analysis was also performed for trace or minor concentrationsof other species in the same samples. Table XIII shows the results ofminor species characterization of the 11 liquid samples. Generally, thedata suggests that the solids separator 500 achieved good removal (>95%)of the minor polyvalent cations (barium and strontium) from all types ofregenerant waste liquid 376.

TABLE XIII Fe³⁺ Ba²⁺ Sr²⁺ K⁺ Mn As Zn Cu (mg/L) (mg/L) (mg/L) (mg/L)(mg/L) (mg/L) (mg/L) (mg/L) Brine Only Supernatant BDL 0.328 1.65 4200.08 1.57 1.64 1.22 Filtrate BDL 0.396 1.58 451 0.04 0.46 0.52 1.69Brine BDL 11.200 149.92 366 1.23 0.38 5.07 1.97 Rinse Only SupernatantBDL 0.328 1.50 266 0.06 1.12 0.64 1.53 Filtrate BDL 0.257 1.04 281 0.020.57 0.23 1.71 Brine BDL 8.300 96.13 234 0.97 8.10 1.12 1.75 Brine +Rinse Supernatant BDL 0.492 3.88 417 0.01 0.55 0.23 1.31 Filtrate BDL0.903 7.40 397 0.01 0.44 0.38 1.73 Brine BDL 9.100 102.54 337 1.12 0.552.77 1.96 Sweet Brine BDL 0.105 2.30 BDL 4.29 2.53 0.56 5.00 ReclaimedBrine BDL 15.500 185.80 438 1.61 0.68 1.23 3.74 Alkalinity Ni Pb Cd SiO₂(mg/L as HCO₃ ⁻ CO₃ ²⁻ (mg/L) (mg/L) (mg/L) (mg/L) CaCO₃) (mg/L) (mg/L)Brine Only Supernatant 0.10 0.05 0.0018 34.67 805 981 0.38 Filtrate 0.110.07 0.0011 22.90 660 799 3.03 Brine 0.39 0.19 0.0020 9.39 70 85 0.02Rinse Only Supernatant 0.17 0.04 0.0009 18.32 1510 1839 1.08 Filtrate0.07 0.03 0.0014 31.67 1120 1363 1.24 Brine 0.32 0.20 0.0044 11.51 135165 0.05 Brine + Rinse Supernatant 0.05 0.02 0.0004 4.00 25 30 0.00Filtrate 0.11 0.04 0.0005 11.00 105 75 24.05 Brine 0.44 0.13 0.0085 7.4775 91 0.02 Sweet Brine 0.06 0.11 0.0079 8.79 105 128 0.08 ReclaimedBrine 0.40 0.08 0.0004 8.58 90 110 0.02 BDL: below detection limit

Further, with the exception of arsenic, none of the other trace metalswas detected at concentration levels of concern. Arsenic was found atlevels of concern in both the “sweet” brine and “rinse only” brine. Thisseems anomalous since all other samples were moderate or low. Arsenic isnot expected to be significantly removed with hydroxide/carbonate ashtreatment, so the concentration in the influent brine should be similarto that in the supernatant and filtrate. The leaching tests of solidsamples (see following section) did not indicate high arsenic in any ofthese results, substantiating that transfer to the solids was notoccurring. All of these factors suggest that sample contamination wasthe cause of the high values rather than high arsenic in the liquidphase. The high concentration samples, as well as random additionalsamples, are being reanalyzed to attempt to identify the source andnature of the problem. A supplement to this memo will be reported, ifsubsequent analyses indicate the problem may not be samplecontamination.

Table XIII also showed that silica levels are high enough in all samples(regenerant waste liquid 376 and baseline brines) to cause fouling insome treatment processes (e.g., membrane filtration), but not so high aslikely to cause problems in ion exchange or solids separation andsettling. Further, the alkalinity of all the waters is low relative tohardness. This further verifies that precipitation hardness removal iscarbonate limited.

2. Characterization of Solid Samples

In this experiment, filter cakes 534 were collected from in the filterpress 520 and chemically analyzed to determine its chemicalconstituents. Regenerant waste liquid 376 comprising spent regenerantsolution 100 of brine only was treated in the filtration unit 594 toform the filter cakes 534. Approximately a 5-lb sample of the dewateredfilter cakes 534 was collected from the filter press 520. This sample isthe solid fraction corresponding to the liquid fraction filtrate sampleof the “brine only” regenerant waste liquid 376 discussed in theprevious section. The sample was maintained at 4° C. until used forleaching tests.

Table XIV shows the results of the various leaching tests of the filtercakes 534 with the metals analyzed and their concentrations in thesolution phase. Four leaching tests were used to characterize thesuitability of the dewatered solid for non-hazardous disposal, such asin a municipal solid waste landfill, including:

1) EPA mandated Toxicity Characteristic Leaching Protocol (TCLP);

2) California Waste Extraction Test (WET);

3) Landfill leachate test, which is a modified version of the TCLP thatuses actual landfill leachate instead of acetic acid as the extractant;and

4) Aqueous solubility test which measures solubility of solid species inpure water to simulate rainfall percolation.

In addition, a sub-sample solid was completed, digested using aquaregia, and the major metal composition of the digestion liquid wasanalyzed to ascertain the primary quantitative mineralogic compositionof the solid. Elemental analysis was done on ion chromatograph. Thewater content of the filter cakes 534 was quantified so that thequantitative composition could be reported on a dry weight basis.

TABLE XIV Metal concentrations solubilized by leaching tests of softenedbrine sludge. EPA Regulatory Landfill Aqueous HW CAS Level TCLP WETLeachate Solubility No.¹ Contaminant No.² (mg/L) (mg/L) (mg/L) (mg/L)(mg/L) D004 Arsenic 7440-38-2 5 0.008580 0.006630 0.024070 0.009400 D005Barium 7440-39-3 100 4.592030 0.583782 0.268918 0.194772 D006 Cadmium7440-43-9 1 0.000130 0.000010 0.000130 0.000010 D008 Lead 7439-92-1 50.009260 0.001149 0.002370 0.000220 Silica (SiO₂) NAL 46.14521423.280186 16.898684 13.577984 Manganese NAL 0.127000 0.019200 0.1330000.002350 Nickel³ 1,000 0.029100 0.003440 0.014300 0.001960 Copper⁴ 1000.911667 0.249637 0.083600 0.013800 Zinc NAL 2.397097 0.017800 0.0501000.007590 Strontium NAL 56.317349 7.537682 2.769459 1.686690 Notes:¹Hazardous waste number. ²Chemical abstracts service number. ³10X MCLunder considered as surrogate regulatory limit ⁴100X Secondary drinkingwater standard as surrogate regulatory limit NAL: no action limit

The chemical analysis revealed that none of the metals were present inthe filter cakes 534 in a concentration that is above the maximumpermissible limit that would designate the filter cakes as a hazardousmaterial. Generally, the leached concentrations were less than 5% of themaximum permissible limit that delineates a solid material as hazardousdue to toxicity. The TCLP test was the most aggressive of the leachingtests with regard to the filter cakes 534 produced by treatment of the“brine only” sample. This is expected for a solid that is predominantlycomposed of carbonate and hydroxide minerals, which will increase insolubility in the acidic pH range and the presence of a complex formingligand. Also, for certain metals, toxicity characteristic limits havenot yet been established by EPA, but primary or secondary drinking waterstandards exist. If a primary standard does exist, the comparative limitwas set at ten times the primary standard as a conservative response tothe normal protocol of setting the TC at 100-fold the primary standard.For metals with only a secondary (non-binding) standard, the comparativelimit was set at one hundred times the secondary standard. The leachingtest results suggest that the filter cakes 534 can be sent to municipalsolid waste (MSW) landfills, or can be used in other non-hazardousbeneficial use. Further, the sludge sample water content was 52% whichwould pass the Paint Filter Test for disposal in a MSW landfill.

3. Solid Composition Results and Discussion

The chemical composition of the compounds in the filter cakes 304derived from a regenerated waste liquid 376 were estimated bycalculations as shown in the pie chart of FIG. 12. The analysis wasbased on measurement of major cations plus sulfate using ionchromatograph and calculation of the major mineralogic componentsassuming only carbonate, hydroxide and sulfate family minerals arepresent.

It can be seen from the compositional analysis that calcium carbonateand magnesium hydroxide make up more than 95% of the mass of the filtercakes 534. This was expected from the relative proportion of calcium andmagnesium ions extracted from the spent resin 60 by the regenerantsolution, which end up in the spent regenerant solution 100, and whichin turn forms part of the regenerant waste liquid 376. Further, thecalculated mass was within 0.6% of the measured dry mass, suggestingthat the contribution of unaccounted-for trace minerals is negligible.

A separation process can be used to separate the Mg(OH)₂ solid fractionfrom the CaCO₃ solid fraction from the relatively high volume fractionof magnesium hydroxide and calcium carbonate in the filter cakes 534. Inone version, such a separation process comprises a two-stepprecipitation process. In the first stage, a first regenerant treatmentcomposition 111 a can be added to the regenerant waste liquid 376 toraise the pH of the liquid above 11. The first regenerant treatmentcomposition 111 a can include, for example, hydroxide compounds such assodium or calcium hydroxide. In the first stage, magnesium hydroxidewould precipitate out of regenerant waste liquid 376 as the filter cakes534 in the filter press 520. A second treatment stage can then beperformed on the regenerate waste liquid 376 by the addition ofcarbonate compounds (e.g., sodium carbonate) to force the precipitationof calcium carbonate from the waste liquid 376. This may be of interestif the filter cakes 534 can be used to generate compounds such asfeedstock for cement manufacture and many other applications.

Example 6 Filtration Unit Additional Testing

In this example, additional batches of regenerant waste liquid 376having different compositions were treated in the solids separator 500to further characterize the treatment process and refine operatingprocedure. Liquid samples were collected from four points in themodified treatment sequence for chemical analysis of the composition ofthe liquid. One position was sampled at three different times (i.e.,early, middle and late in run). Thus, a total of six samples werecollected for analysis. The sample identities and labeling were:

(1) spent regenerant solution—(raw water) RW (1 sample);

(2) supernatant pre-filtration & CO₂—SPRE (1 sample);

(3) supernatant post-filtration & CO₂—SPOST (3 samples); and

(4) filter press filtrate no CO₂—FPF (1 sample).

The six liquid samples collected were analyzed for major ions andaggregate parameters, as shown in Table XV:

TABLE XV Hardness Alkalinity HCO₃ ⁻ CO₃ ²⁻ TDS Na⁺ Ca²⁺ Mg²⁺ K⁺ Cl⁻ SO₄²⁻ (mg/L as (mg/L as (mg/L) (mg/L) (mg/L) Turbidity TOC Sample (g/L)(mg/L) (mg/L) (mg/L) (g/L) (mg/L) pH CaCO₃) CaCO₃) (calc.) (calc.)(calc.) (NTU) (mg/L) SPOST 1 42.1 64.8 13.92 230.83 56.26 39.04 12.57219 9333 25.84 4458 98560 3.94 10.38 SPOST 2 53.9 72.8 9.12 306.43 71.9634.33 12.63 219 9824 23.16 4587 116416 7.11 8.98 SPOST 3 42.7 65.6 13.44244.20 56.64 43.26 12.57 219 7491 19.46 3357 98496 7.46 9.09 FPF 51.072.8 11.52 301.00 69.00 37.14 12.64 229 10438 24.73 4942 116224 3.727.51 SPRE 44.4 80.8 9.12 253.22 59.01 37.06 12.60 239 9579 24.63 4531114240 3.48 10.14 RW 39.8 5608 1195 254 71.84 40.40 6.73 18918 521634.92 0.16 98432 521.10 3.33

In this experiment, the mineral hardness levels in the spent regenerantsolution samples were considerably less than those of Example 5 whichwere 47,574 mg/L. This occurred because the spent resin 60 that wasregenerated to form the spent regeneration solution 100 and resultantwaste liquid 376 was not fully exhausted, which is a large inefficiencyin the current process.

While the regenerant waste liquid treatment process removed over 98.5%of the hardness of the waste liquid 376, it did not achieve the sameremoval level as was observed in Example 5. It is believed that thelower magnesium removal rates occurred because of (i) too short asettling period after the regenerant treatment composition 111 was addedto the waste liquid 376, (ii) too low a total suspended solidsconcentration in the waste liquid 376, or (iii) too low a pH of thewaste liquid 376 after addition of the treatment composition 111. Thesolids concentration is significantly higher than typical in drinkingwater treatment applications that yield good results, and the pH in allsamples was greater than 12. Thus, it was most likely that either thesedimentation tank was not sufficiently quiescent for good aggregationand settling, or the sedimentation time was too short. These problemswould also result in poorer than expected calcium removal. It is furtherbelieved that the precipitation yields can be improved by maintaining aslow agitation of the regenerant waste liquid 376 after addition of thetreatment composition 111 in the regeneration vat 140.

The sodium concentration of the water being softened (RW) was lower thanthe “rinse only” regenerant waste liquid 376 in Example 5 due toanomalies in the salt content of the spent regeneration solution 100 andother factors. Comparing the SPOST to the SPRE, modest additionalmineral hardness removal (about 8.5%) from the regenerant waste liquid376 was achieved with aeration induced CO₂ (carbon dioxide gas) additionprior to filtration. The treated regenerant liquid 342 contained about30% of the sodium of the fresh regenerant solution 186 (or “sweet brine”solution), and about 50-60% of the sodium of normal resin regenerationinfluent. This can be changed by using NaOH rather than Ca(OH)₂ foradjustment of the pH of the treated regenerant liquid 342. This canincrease the final sodium concentration of the treated regenerant liquid342 and decrease the volume of the filter cakes 534 but may be morecostly.

Thus, the solids separator 500 was determined to provide sufficientlylow levels of multivalent ions 424 in the treated regenerant liquid 342to allow recycling and recovery of the accreted regenerant solution,regardless of the differences in chemical concentration of theconstituents of the treated regenerant liquid 342 in Examples 5 and 6.

Example 7 Evaluation of Nanofiltration and Reverse Osmosis Membranes

In this example, the regenerant waste liquid 376 treated in the solidsseparator 500, as described in Examples 5 and 6, was further treatedwith nanofiltration (NF) and reverse osmosis (RO) membranes to furtherpurify the waste liquid 376 to form pure water. In this experiment, alarge volume of 30 gallons of SPOST composite water was collected fortesting using a range of NF and RO membranes to ascertain the waterrecovery and salt rejection capability of the process on SPOST water.One 10-gallon sample of the FPF (non-CO₂ adjusted) sample was collectedfor NF/RO treatment evaluation from Example 5. For promising membranes411, concentrate 418 and filtered liquid 417 samples were to becollected with subsequent thermal or mechanical distillation of the mostpromising concentrate sample.

TABLE XVI Membrane Area Ec_(initial) EC_(conc) EC_(perm) P_(feed)Q_(perm) Vol_(init) Vol_(final) A Rej Qfeed Membrane Type (cm{circumflexover ( )}2) (mS/cm) (mS/cm) (mS/cm) (psi) (psi) (L) (L) (cm/s/psi) (%)(L/min) RO-SAEHANV4040-FE 125 181.2 NA NA 300 NA 9.00 9.00 NA NA 1.89NF-ESNA1-LF-4040 125 164.6 178   158.1 320 1.779 10.50 3.70 7.42E−0711.18  1.89 NF-Filmtec 270 4040 125 181.2 187.1 176.2 320 17.43 9.002.70 7.27E−06 5.83 1.89 NF-Koch 4720 SR2 276 180.6 180.8 175.7 85 11.979.55 3.45 8.56E−06 2.82 0.40 RO-ESPA1 84 183.9 183.9 173.8 300 0.12 5.004.90 8.17E−08 5.49 1.89 RO-ESPA1 276 193.9 NA NA 90 NA 9.55 9.55 NA NA0.40 Permeation and salt rejection results for SPOST 2 feed water tovarious Nanofiltration and Reverse Osmosis membranes.

Table XVI shows the results of testing membranes using SPOST 2 water. Inall cases, turbidity of influent, filtered liquid 417 and concentrate418 was measured, and in no case was it above detection. However, thepermeation flux was low with Typical RO water transport coefficientsbeing in the range of 10⁻⁴ to 10⁻⁵ cm/s/psi. The measured rates weremore than 700 fold lower than typical and for one RO membrane at 300psi, no permeation was observed. The highest salt rejection was about11%, meaning for the pressures used nearly 90% of the influent saltpassed through the membrane. The problem is that water permeation is soslow that the salt diffusion rate is comparable to the water permeationrate.

A calculation of the osmotic pressure of the brine influent solutionsindicates that a transmembrane pressure of greater than 1000 psi wouldbe required to create appreciable permeation of waste liquid 376 throughthe membrane 411 with high salt rejection.

The system and processes described above allow ion exchange resins 22 toabsorb undesirable ions from fluid passed through the resin, and thenregenerate the exhausted or spent resin 60 after a time period when theycan no longer absorb ions from the liquid. The spent resins 60 areregenerated with minimal wastage of regenerant solution 186, recovery ofchemicals used in the regeneration process, reduced water usage, andreduced environmental impact of disposing of spent regenerant solution100 and other materials into the environment.

The present invention has been described with reference to certainexemplary or preferred versions thereof; however, other versions arepossible. For example, the apparatus and methods can be used in othertypes of applications as would be apparent to one of ordinary skill,such as, for example, other ion exchange processes for removing othermaterials or ionic species from liquids, solutions, and slurries. Thesystem can also have other configurations of the regeneration wastesolution apparatus, different ways of interconnecting the various sumps,vats, and tanks, alternative valve systems or pumps, and differentregenerant solution compositions or chemicals. Therefore, the spirit andscope of the appended claims should not be limited to the description ofthe preferred versions contained herein.

Furthermore, in this description, embodiments of the present inventionwere described with reference to specific embodiments; however, it willbe appreciated that various modifications and changes may be madewithout departing from the scope of the present invention as set forthin the exemplary provisional embodiments. The specification and figuresare to be regarded in an illustrative manner rather than a restrictiveone, and all such modifications are intended to be included within thescope of the present invention. Accordingly, the scope of the inventionshould be determined by the claims and their legal equivalents. Forexample, the steps recited in any method or process claims may beexecuted in any order and are not limited to the specific orderpresented in the claims. Additionally, the components or elementsrecited in any apparatus embodiment may be assembled or otherwiseoperationally configured in a variety of permutations to producesubstantially the same result as the present invention and, accordingly,are not limited to the specific configuration recited in the claims.

Still further, the benefits, other advantages and solutions to problemshave been described above with regard to particular embodiments;however, any benefit, advantage, solution to problems or any elementthat may cause any particular benefit, advantage or solution to occur orto become more pronounced are not to be construed as critical, requiredor essential features or components of any or all the provisionalembodiments. As used herein, the terms “comprising”, “having”,“including”, or any variation thereof are intended to reference anon-exclusive inclusion, such that a process, method, article,composition or apparatus that comprises a list of elements does notinclude only those elements recited but may also include other elementsnot expressly listed or inherent to such process, method, article,composition or apparatus. Other combinations or modifications of theabove-described structures, arrangements, applications, proportions,elements, materials or components used in the practice of the presentinvention, in addition to those not specifically recited, may be variedor otherwise particularly adapted by those skilled in the art tospecific environments, manufacturing specifications, design parametersor other operating requirements without departing from the generalprinciples of the same.

What is claimed is:
 1. A resin regeneration system comprising: (a) aregeneration vat for holding spent cation exchange resin; (b) aregenerant solution tank for holding fresh regenerant solution, theregenerant solution tank is connected to the regeneration vat to allowtransfer of the regenerant solution into the regeneration vat toregenerate the spent cation exchange resin to form fresh cation exchangeresin and spent regenerant solution; (c) a regenerant recovery tankcomprising (i) a fluid inlet to receive the spent regenerant solution,and (ii) a fluid outlet to release treated regenerant liquid; (d) achemical dispenser to dispense a regenerant treatment composition intothe spent regenerant solution in the regenerant recovery tank to form atreated regenerant liquid and precipitate flocs; (e) a solids separatorto receive the treated regenerant liquid and separate the precipitateflocs from the treated regenerant liquid to form a separated regenerantsolution; (f) a pH adjuster to adjust the concentration of chloride ionsin the separated regenerant solution to form fresh regenerant solution;and (g) a pump to pump the fresh regenerant solution to the regenerantsolution tank to regenerate additional spent cation exchange resin.
 2. Asystem according to claim 1 comprising a backwash supply tank to holdbackwash water to backwash the spent cation exchange resin to form spentbackwash water comprising resin fines, and backwash nozzles in theregeneration vat to pass a stream of backwash water upwardly through thespent cation exchange resin.
 3. A system according to claim 2 comprisinga particle filter to filter out the resin fines from the spent backwashwater.
 4. A system according to claim 1 comprising a water softener orthermal distiller to generate rinse water to rinse the spent cationexchange resin after regeneration.
 5. A system according to claim 1wherein the chemical dispenser comprises a hopper connected to a liquidchannel, the hopper having an inlet to receive the regenerant treatmentcomposition and an outlet to dispense the regenerant treatmentcomposition into a flowing stream of the spent regenerant solutionpassing through the liquid channel.
 6. A system according to claim 1wherein the regenerant recovery tank comprises a circulation mixer tomix the spent regenerant solution and dispersed regenerant treatmentcomposition.
 7. A system according to claim 1 wherein the solidsseparator comprises a filter press.
 8. A system according to claim 1wherein the solids separator comprises a centrifuge.
 9. A systemaccording to claim 1 wherein the pH adjuster comprises: (i) apH-adjuster tank for holding a chloride-containing acid; (ii) apH-adjusting tank to hold the separated regenerant solution, the tankcomprising an inlet to receive the chloride-containing acid from the pHadjuster tank; and (iii) a pH-adjuster feed pump to pump thechloride-containing acid from the pH-adjuster tank to the inlet of thepH-adjusting tank.
 10. A system according to claim 1 wherein theregenerant recovery tank comprises a translucent portion.
 11. A resinregeneration system comprising: (a) a regeneration vat for holding spentcation exchange resin; (b) a regenerant solution tank for holding freshregenerant solution, the regenerant solution tank is connected to theregeneration vat to allow transfer of the regenerant solution into theregeneration vat to regenerate the spent cation exchange resin to formfresh cation exchange resin and spent regenerant solution; (c) aregenerant recovery tank comprising (i) a fluid inlet to receive thespent regenerant solution, and (ii) a fluid outlet to release treatedregenerant liquid; (d) a chemical dispenser comprising a hopperconnected to a liquid channel, the hopper having an inlet to receive theregenerant treatment composition and an outlet to dispense theregenerant treatment composition into a flowing stream of the spentregenerant solution passing through the liquid channel to form a treatedregenerant liquid and precipitate flocs; (e) a solids separator toreceive the treated regenerant liquid and separate the precipitate flocsfrom the treated regenerant liquid to form a separated regenerantsolution; (f) a pH adjuster to adjust the concentration of chloride ionsin the separated regenerant solution to form fresh regenerant solution;and (g) a pump to pump the fresh regenerant solution to the regenerantsolution tank to regenerate additional spent cation exchange resin.